science unit 1 biology 10

8/6/2019 Science UNIT 1 Biology 10

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EXAM REVIEW

1.1 Studying the Structure of Cells

Microscopes and Human Health

y Scientists discovered through use of microscopes that germs cause diseases

y A Cell is the smallest unit that can perform the functions of life

y Microscopy is the science of using microscopes to view samples or objects

Types ofMicroscopes:

y Leeuwenhoek microscope: 250x

y Bright field/dark field microscope: 2000x

y Fluorescence microscope: 1500x

y Transmission electron microscope: 1 000 000x

y Phase-contrast microscope: 1500x

y Scanning electron microscope: 200 000x

Cell Structuresy A Nucleus is the organelle that controls the cells activities

y Organelle is a specialized structure in a cell

y One of the first cell structures scientists could see with early microscopes was the nucleus

y Micrograph is a photograph taken with a microscope

The Cell Theory

y Theory of cells was developed in the mid-1800s

1. All living organisms are made of one or more cells.

2. The cell is the basic organizational unit of life.

3. All cells come from pre-existing cells.

Contents of the Cytoplasm

y Fluid material between cell membrane and nucleus-cytosol- is filled with many specialized organelles

y Together, the Cytosol and the organelles it contains are called the cytoplasm

Animal and Plant Cell Organelles

y Many organelles are involved in the production, storage or transport of proteins

y All cells in body depend on proteins, which allow cells to carry out life processes that keep you healthy

List of Cell Organelles and their Functions

Nucleolus - makes ribosomes, which help to make proteins (animal and plant)

Nucleus -controls all cell activities (animal and plant)

Chromosome -in a nucleus, a thread-like structure made mostly of DNA (animal and plant)

Mitochondrion -where energy is released from glucose to fuel cell activities (animal and plant)

Cell Membrane - separates the inside of the cell from the external environment; controls the flow of materials into and

out of the cell (animal and plant)

Cytoplasm -includes the cytosol, the organelles and other life-supporting materials such as sugar and water, all

contained by the cell membrane (animal and plant)


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Ribosome -help to produce proteins, which make up much of a cells structure and are required for activities necessary

for the cells survival; some ribosomes float in the cytoplasm, others are attached to the endoplasmic reticulum (animal

and plant)

Endoplasmic Reticulum -a network of membrane-covered channels that transport materials made in the cell; is

connected to the nucleus (animal and plant)

Golgi Apparatus -sorts and packages proteins and other molecules for transport out of the cell (animal and plant)

Lysosome -destroys worn-out or damaged organelles, get rid of waste materials, and protect the cell from foreign

invaders (mostly animal)Centriole -helps a cell to divide (animal)

Chloroplast -trap energy from the Sun to make glucose, which is broken down in the mitochondria to power cell

activities (animals must get glucose from the food they eat) (plant)

Cell Wall -a tough, rigid structure lying just outside a plants cell membrane; provides support for the cell (plant)

Vacuole -contains water and other materials and are used to store or transport small molecules; plant cells tend to have

one large vacuole; animal cells may have several smaller vacuoles (animal and plant)

Flagellum - whip-like tails that are used to propel a cell in a specific direction (mostly animal)

Cilia - microscopic, hair-like projections on epithelial cells that may secrete mucus and help to keep foreign particles out

of the body (mostly animal)

Animal Cell Diagram


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Plant Cell Diagram

1.2 Genes

The Nucleus

y The master set of instructions that determines what each cell will become

y The instructions are in chromosomes

y Every organism has a specific number of chromosomes

y Chromosomes are made ofDNA

The DNA (deoxyribonucleic acid)

y Model created by Watson and Crick in 1953

y Double-helix structure (twisted ladder shape)

y Has 4 types of building block molecules (A: adenine, T: thymine, C: cytosine, G: guanine)

y There is complementary base paring in DNA; A-base pairs with T-base, C-base pairs with G-base

y DNA is divided into segments called genes

y Genes provide instruction for making protein

y The order which A, T, C, and G building blocks are strung together is called genetic code

y The genetic code is different in everyone

Why is DNA important?

DNA controls your features (hair, eye colour) and whether you can digest certain foods (e.g. lactose in milk). It does this

through the production of proteins.

DNA Screening

y Tests for the presence of genetic disorder in the fetus

y Amniocentesis is a technique via which a needle is inserted into the pregnant womans abdominal wall to

withdraw a sample of fluid from the amniotic sac (surrounding the fetus)

y Cells from fetus are isolated and a micrograph (small picture) of the chromosome is taken


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y The karyotype (appearance of chromosome makeup) will show if it has too many or too few or broken

chromosomes [e.g. genetic disorder Downs Syndrome]

Some Genetic Disorders

y Phenylketonuria (PKU): if uncorrected, can lead to severe brain damage

y Huntington Disease: affects the nerve cells. Symptoms appear in a persons 40s and include loss of muscular

control and brain function. Persons health worsens for 15 years before death

Ethical Issues and Drug Researchy Research into treatment for various diseases is carried out by drug companies.

y Once a company develops a drug that is effective and safe, it conducts a clinical trial on humans.

y In Canada, approval for drugs is given by Health Canada.

y BUT clinical trials can be biased.

y Companies can present trial data as more positive than they really are because they want to sell their drug.

y As well, if a company makes a discovery for a disease that is effective, would this company then own the right to

sell the drug in any way it chooses?

Altering Genes: Benefits and Controversies

y Genetic engineering - when you combine DNA from different species. The species whose genes are altered are

genetically modified organisms (GMOs) or transgenic organisms.Concerns

y People are concerned about the long-term consequences of eating GMO plants.

y There is also concern of what GMO plants do to the ecosystem in terms of spreading to other areas or posing as

competition to natural species.

Cloning

Simple cloning: take cuttings from a plant; root them and thereby producing more plants that are exact copies

of the parent plant

Steps:

1. Remove the cell nucleus of an egg from a female sheep

2.A cell is removed from an adult sheep. This cell and the egg cell are placed next to each other in a bath of

chemicals

3. A jolt of electricity causes the 2 cells to fuse

4. The fused cell begins dividing to form an embryo

5. The embryo is then inserted to the uterus of a surrogate mom to complete its development. The resulting lamb

is a clone of the sheep that donated the adult cell.

Mutations

y A change in the usual order of the A, T, C, G building blocks results in a change in the structure of the protein

that is produced. This change can then affect how well the protein does its job.

y Mutations can easily be caused by the mutagens which are forces or substances that physically damage the

DNA. For example, electromagnetic radiation including x-rays andUV rays and chemicals (mercury, tar in

cigarettes)

y Not all mutations are harmful because they only part of a DNA molecule contains genes, the rests does not code

for proteins. A mutation that occurs of a non-genetic part of a DNA molecule is not harmful.

y Can science fix mutations? Gene therapy is the research/science that corrects faulty genes.


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Anaphase

y The centromere splits up the chromosome (now chromatids)

y The chromatids are pulled to opposite sides of the cell by spindle fibres towards the centromeres

y The cell has twice as many chromosomes as usual

Telophase

y Spindle fibres start to disappear

y Nuclear membrane starts to form around the two new nuclei along with the nucleolus

y The cell membrane starts to pinch in

y Chromatids start to thin out into chromatins

The Second Stage in Cell Division: Cytokinesis

y The division of the rest of the cells (cytosol and organelles) begins during telophase

y In animal cells, the membrane starts to pinch in until the parent cell completely divides into two parts

y In plant cells, the golgi body start to form vesicles that line up in between the two nuclei

y The vesicles starts to form the cell plate; a structure that helps to form the cell wall


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1.4 The Cell Cycle

Type of Body cell Average Life

Span

Brain 30-50 years

Red Blood 120 days

Stomach Lining 2 days

Liver 200 days

Intestine Lining 3 days

Skin 20 days

Stages of the Cell Cycle

Cell cycle is a continuous sequence of cell growth and division (interphase, mitosis, and cytokinesis)

Interphase is the periods of growth during the life of a cell

- consists of two growth stages and a DNA replication stage

Checkpoints: Can This Cell Pass?

Cell cycle checkpoints are a point in the life of a cell when proteins determine if division should or should not occur

- Specialized proteins act like stop signs at each checkpoint

- Cell division will not occur if:

1.

There are not enough nutrients to support the cell

2. The DNA has not replicated

3. The DNA is damaged

y Many cells usually leave the cycle at this point and enter a non-dividing stage

y Muscle and nerve cells are in the non-dividing stage

Cell Death

y Some cells leave the cycle to die

y Cells die due to being damaged beyond repair

y The contents of the cell leak out, irritating surrounding cells and causing swelling in the area

Cell Suicide

y Sometimes a cell breaks down in an organized way

y Its contents are packaged and distributed so other cells can use them

y Some cells have this death pre-programmed into them determined by suicide genes

y Suicide genes are responsible for human finger and toe development

Cancer and the Cell Cycle

y Some cells ignore the checkpoints and start to divide excessively

y This forms a clump of abnormal cells called a tumor

y The abnormal clump of cells can become cancer


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y Cancer is cells that contain abnormal genetic material and divide uncontrollably and can also spread to other

places

y These abnormal cells take up space and use up nutrients that are needed by other cells

Losing Control

y Most cells are attached to a surface while dividing

y Once its not attached, it stops dividing but cancer cells have a mutation that keeps them dividing regardless

y Most cells can divide 20 to 30 times and then carries out the programmed suicide

y Loss of control of the cell division can be inherited from ones parents or from being around mutagensy Mutagens that lead to cancer are called carcinogens (asbestos, tobacco smoke, etc)

2.1 Plant Cells, Tissues, and Organs

Cell Specialization

Cell Specialization is the process which cells develop from similar cells that have specific functions

Cell Differentiation is a stage of development of a living organism during which specialized cells form

y Cells are specialized according to the set of proteins that they contain

Specialized Cells and Tissue in Plants

y A plant is always growing and making new specialized cells

y Some specialized cells form tissue

Tissue is a cluster of similar cells that work together and perform a specific function

Organs are a combination of several types of tissue working together to perform a specific function

Meristematic Cells are unspecialized plant cells that can form into specialized cells

Meristematic cells constantly produce more and more cells, then they become specialized in a cluster

These cells can form into three different types of tissue:

Dermal tissue: skin of the plant, a barrier between the plant and its external environment

Groundtissue: has many functions- some cells can perform photosynthesis, others support the stem

Vasculartissue: transports water, nutrients, and sugars throughout (phloem and xylem)


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Repairing and Replacing Specialized Cells

y Plants form new organs periodically

y For example, leaves become less efficient with age, these old leaves are replaced by new and more

efficient leaves

y Plants grow upward, downward, and outward because of the dividing unspecialized cells

y A bud is a swelling of a stem the contains unspecialized cells for new and not yet developed tissues

such as the leaves and stem

y

A plants most active growth occurs near the terminal bud

Growing Up or Branching Out

y Plants that are growing give off a chemical called auxin (plant hormone)

y Auxin controls the cells below and behind them

y Auxin can control where to develop and hold back a plant, which is why terminal buds are growing

more upward than outward (the auxin holds the lateral buds back from developing)

y If you remove the terminal bud, the auxin starts to release in the lateral buds, making the plant more

bushy

Tissues Working Together

y Flowering plants only have three or four organs

y Three of them make up the body of the plant: stem, leaf and root

y The fourth is the reproductive organ (the bud/flower)

y Organs make it possible for the plant to live

The Leaf

y Provides a large surface area so photosynthesis can occur

y If photosynthesis produces more glucose than it needs, it turns into starch and is stored in the leaf

The Upper and Middle Leaf

y Main function is to protect (does not perform photosynthesis)

y Upper surface of the lead is made of dermal tissue and is called the epidermis

y The epidermis secretes a waxy cuticle which helps reduce the amount of water that evaporates from

the leaf


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y Between the upper and lower surface of a leaf is called the mesophyll tissue

y The mesophyll tissue consists of palisade tissue cells and spongy parenchyma cells

y Palisade cells perform most of the photosynthesis in the cell

y Parenchyma cells are loosely packed to form a network with open spaces and contains gases produced

or needed by photosynthesis: water vapour, oxygen and carbon dioxide

y At the centre of the leaf is the phloem and xylem tissue arranged in a vascular bundle

y The xylem delivers water to the photosynthesizing cells

y Phloem picks up sugar and nutrients and delivers to the cells throughout the rest of the plant

The Lower Leaf Surface

y Made up of epidermis that is critical for the exchange of gases between the leaf and the outside

environment

y Guard cells allow gases to move in and out of the lower surface of the leaf

y These cells change shape to control the opening and closing of the pores in the leaf (stoma/stomata)

y Guard cells and stomata play a large role in transpiration

y Transpiration is the evaporation of water from the leaves

y Carbon dioxide enters through the stomata, oxygen and water vapour exit through them

The Stem

y Two main functions: physical support and transportation of water, nutrients and sugars

y Contains most of the xylem tissue (long pipes for water to flow through)y The xylem and phloem are stacked together in vascular bundles

The Roots

y Anchors the plant to the ground and allows it to take up water and minerals from the soil

y Also acts as a storage area

y Cortex cells do not contain chlorophyll and is mainly used by the plant to store starch

y The endodermis helps control the transport of minerals between the cortex and vascular bundles

y The pericycle is a layer of tissue that surrounds the xylem and phloem


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Plant Galls

Gall is an abnormal growth of plant tissue caused by insects or micro-organisms

y Plants produce galls in response to attacks by organisms such as bacteria, viruses, insects, etc

y Insects promote the development of galls by injecting a chemical into a plants tissues which alters the

plants genes and stimulates a growth of a structure

y Plant galls dont normally spread to other tissues like animal tumors do

y

Galls usually dont affect a plants normal functions

The Reproductive Organ: The Flower

y The flowers main task is to reproduce

y The different parts of the flower (petals) are just specialized leaves

y One set of the leaves is specialized to producepollen which is the sperm of a flower

y Another set of the leaves produces eggs

y Transfer of pollen from flower to flower is fertilization

2.2 Plant Organ Systems

Systems are a group of tissues and organs that perform specific functions

Root System is an organ system in a plant, which takes in water and minerals from the soil and transports

these substances to the shoot system

Shoot System is an organ system in a plant which supports the plant, performs photosynthesis and transports

sap

y Root system is underground; shoot system is above ground

SystemsWorking Together

y Root and shoot systems are connected by the flow of water, nutrients and various hormones through

the xylem and phloem

y Xylem takes care of moving water and minerals from the roots to the other parts of a plant

y Phloem moves the sugars produced by photosynthesis to other plant parts


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Moving Water through the Systems

y Water is the most essential thing to a plant

y Nutrient molecules need to be dissolved in water in order to be absorbed and moved by the xylem

y Photosynthesis cannot take place if there is too little water

y Too little or too much water is very bad for the plant

y If theres too much water, there would be no room for the plant to breathe and would drown

Moving Through the Rootsy Epidermal cells of most roots grow small extensions called root hairs

Root Hairs help expand the roots total surface area

y Water and nutrients in the soil are transported into the roots by osmosis

y Then it moves towards the xylem to be transported throughout the plant

The Effect of Root Pressure on Water Movement

Root Pressure is created so that the water and nutrients in the plant can move upward

y Created when transpiration is low and the soil is very moist

y Root cells bring minerals into the xylem, the concentration of minerals increases

y

As water flows in, the pressure increases even more, now pushing the water and minerals up the xylem

y Root pressure is usually not strong enough to push water up a tall tree, so transpiration is also used

The Pull from Above

y Xylem tissue ends when it reaches the leaves

y Liquid water turns into water vapour in the spaces in between the spongy parenchyma cells

y The water vapour will eventually be released as the stomata open to take in carbon dioxide and

releases oxygen

Cohesion is the ability for water molecules to cling onto each other, also holds up the water column

Adhesion is the ability for water molecules to stick on to certain surfaces, also helps water to fight gravity

How TranspirationWorks

y Water from the soil enters the xylem in the roots, pressure brings it up to the stem and leaves

y Water columns is held together by cohesion and adhesion keeps it in place

y Transpiration of water from leaves creates tension that pulls on the water column in the xylem

y The sun causes the water to evaporate

3.1 Cells and Tissues

What factors influence Cell Specialization in animals?y Contents of the cells cytoplasm

y Environmental conditions [temperature]

y Influence of neighbouring cells

Effect of Cytoplasm on Cell Specialization

y Although mitosis ensures that daughter cells receive identical sets of chromosomes, the contents of

cytoplasm may be different

y For example, one daughter cell may have more storage vacuoles than the other


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y Having more vacuoles will allow the cell to use more energy as it grows

y Even when an embryo is a couple of hours old, how many cells will specialize will have already been

determined by the differences in the cells cytoplasm

Effect of Environmental Conditions on Cell Specialization

y Temperature and the presence or absence of certain nutrients can influence cell specialization

y

F

or example, Siamese cats produce cells of dark hair colours only when around cool temperaturesy This is why their ears, feet, nose and tail are darker than the rest of their body

Effect of Neighbouring Cells on Cell Specialization

y Nearby cells has the biggest influence on what a cell will become

y When cells are close to each other, sometimes one cell can diffuse through the other cells membrane

y When they diffuse, the substances change how the DNA in the second cell is expressed and the second

cell becomes the same as the first one

WhyA

bnormal Development SometimesO

ccursy Environmental factors play an important role in development and also when things go wrong

y Chemicals in the environment such as pollutants trigger abnormalities

y Some abnormalities are passed on from birth

Similar Cell Conditions Form Similar Cells

y As a cell matures, its genes get turned on or off by the effect of other cells or the environment its in

y Different combinations of active and inactive genes will produce a skeletal muscle cell, another

combination would produce a nerve cell

y Eventually, they will have been matured so much that they remain the same specialized cellsy Cells do not change do not change to become another type of cell after maturity

Types of Tissues

Epithelial

y Lines the surface of the body

y Cells with strong connections between touching cell membranes, so they form a barrier

Skin Epithelia: thin, flat cells that form a sheet, semi-permeable barrier from inside and

outside of a body

Columnar Epithelia: made of columns of cells that line the small intestine and stomach, maysecrete mucus, have cilia and/or absorb materials

Muscle

y Designed to change shape

y Act by shortening or lengthening

Skeletal: made up of cells that line in the same direction, attached to bone, allowing the body

to move

Smooth: made out of cells that are tapered at both ends, found in blood vessels, walls of


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internal organs, contracts slower than skeletal muscle

Cardiac: made of cells with nuclei that seem to be in between cells, contracts as a unit, only

found in the heart

Nervous

y Made of cells called neurons which have finger-like projections, receives and transfers signals

y Coordinates body actions

y Some determine information from environment (whether its hot or cold)

y Others relay signals from brain or spinal cord to muscles and glands

Connective

y Strengthens, supports, protects, binds or connects cells and tissues

Bone: made of cells surrounded by calcium hardened tissue, bloods runs through it, needed

for movement, support and protection

Fat: made of large tightly packed cells, found under skin around organs, needed for energy

storage, padding and insulation

Blood: includes red and white blood cells, transports nutrients and oxygen, clots when skin is

cut and attacks bacteria and viruses

Stem Cells

y An unspecialized cell that can be produced into various specialized cells

y Totipotentstem cells can become any kind of cell in the body (embryonic stem cells)

y Found in the early stages of development (early embryo)

y Pluripotentstem cells are less versatile

y Found later on in development

y

Adult stem cells can only produce specific kinds of cellsy Only skin stem cells can produce skin cells, etc.

y Obtaining stem cells from the embryo destroys the embryo

3.2 Organs and SystemsMedical Imaging Technology has many techniques used to form an image of a bodys cells, tissues and organs

Which Technology is Best?

X-Rays: Electromagnetic radiation is transmitted through the body to expose photographic film on the

other side, best used for hard tissue such as the bone

CT Scan: X-rays of thin slices of a body part later on reconstructed by a computer to produce a 3D

image

Ultrasound:High frequency sound waves directed at a part of the body, shows real-time movement of

the body, mainly used to see foetuses in pregnant women

MRI Scan: Radio signals in a magnetic field to create images of body parts, usually used to detect

bleeding in the brain


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Advances in Diagnosis

y Endoscopyis when a tiny camera and light is attached to a tube and is inserted to your body

y Barium x-rays are used to diagnose a stomach ulcer

The Bodys Organization: A Hierarchy

y The circulatory system moves blood throughout the human body

y

The heart is a major organ of the circulatory systemy Heart tissue made up of muscle cells keeps the heart beating

y Specialized muscle cells form heart tissue

Human Organ Systems

Circulatory

y Transports blood, gases, nutrients and wastes

Digestive

y Takes in food and breaks it down, absorbs nutrients, removes solid wastes from the body

Respiratory

y Controls breathing

y Exchanges gases in lungs

Muscular

y Works with bones to move

Excretory

y Removes liquid wastes from the body

Digestive System

y Begins in the mouth, saliva starts chemical breakdown in foody Passes through thepharynxinto the esophagus which contracts and relaxes, pushing food down

y In the stomach, food chunks are surrounded by gastric juices (hydrochloric acid and pepsin) which

break down proteins

y Stomach starts to churn, mixing the contents and breaking foods down into liquids

y Then the food contents go through the small intestine which completes the chemical breakdown

y Lastly, the broken down food goes through the large intestines which absorbs water, vitamins and

various salts from digested food to be emptied in the anus as feces

Excretory Systemy Takes care of the liquid wastes

y Water and other materials absorbed through the walls of the large intestine and move through the

blood vessels

y Then the kidney filters the blood vessels, urine containing water and unneeded salts is formed

y The urine is stored in the bladder, when full the urine will be flushed from the body


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Circulatory System

y Picks up and transports nutrients and oxygen to cells and carries wastes to the organs responsible for

eliminating them

y When the heart contracts, pressure is put on the blood which circulates it throughout the body

y Valves are found in the heart and veins and they prevent from blood flowing back

y Blood that returns from body is deoxygenated and goes through the right ventricle, which leads it to

thepulmonaryartery, then to the lungs, where the blood picks up oxygeny Then blood goes back to the heart, through the leftatrium, then to the left ventricle and is pumped out

through the aorta to the rest of the body

y Humans have a 4 chambered heart

y Fish have 2 chambered hearts

y Frogs have 3 chambered hearts

Capillaries:Helping Systems Interact

y Are extremely small, thin-walled blood vessels

y

Brings blood into close contact with tissues in organs throughout the bodyy Picks up nutrients and oxygen and delivers it throughout the body

y Also picks up wastes and transports them to the kidneys and lungs to be removed

Respiratory System

y Responsible for the bodys gas exchange, bringing in oxygen and getting rid of carbon dioxide

y Connected to the circulatory system

y When breathing, muscle contractions causes rib cage to move up and out and your diaphragm to move

down

y This causes air to be pulled in through the mouth or nosey Epithelial cells have cilia and secrete mucus that keeps foreign particles such as dust and bacteria out

of your body

y The air moves through the trachea and a muscular flap opens so air can pass

y Then the air passes into branching tubes called the bronchiand the into smaller tubes called the

bronchioles in the lungs

y After the bronchioles, the air passes through more tubes and ends up in the alveoli which are very

close to the bloodstream

y Red blood cells containing haemoglobin pick up the oxygen and travels throughout the body

y When you exhale, the carbon dioxide in the alveoli is carried out of your body

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