1st Semester Review

Cell Structure and Function

Cell Theory

A. Nature of Cells1. Cell theory

a. cell is the smallest unit that still has the characteristics of life.

b. new cells arise from preexisting cells

c. all organisms are comprised of one or more cells.

2. General aspects of cellsa. plasma membranes separate cells from their environment.b. DNA is the hereditary materialc. cytoplasm contains the organelles of the cell.

3. Types of cellsa. prokaryotes: ancient lineage, no nucleusb. eukaryotes: “true nucleus” and membrane bound organelles.

Eukaryotic Cells

A. Organelles1. all eukaryotes contain a nucleus and organelles.2. organelles form compartments in the cytoplasm of the cell3. compartmentalization = specialization4. reactions may be separated and regulated

Plant Cell

Animal Cell

Characteristics of Life

6 Characteristics of Living Organisms

Food getting – ability to get food either by catching it or

making it

Respiration – using oxygen to turn food into

energy (ATP)

Excretion – getting rid of the waste

(CO2, H2O, urea …)

Growth and Development – cell division, aging

Response – reacting to outside stimulus ex. light, temperature …

Reproduction – can make more cells or organisms

Robert Hooke describes the first

cells in 1665.

Antony Van Leeuwenhoek discovered

the first protozoa in 1674. He saw bacteria 9 years later.

In 1838 Theodor Schwann came up with the Cell Theory which

states:

1. All organisms are made up of 1 or more cells.

2. The cell is the basic unit of all living things.

3. Only living cells can produce new living cells.

Cells are the basic unit of all living things ex. unicellular or multicellular

LEVELS OF ORGANIZATION

Tissue is made up of like cells that perform a specific function ex. blood, bone, muscle

Organs are made up of different tissues that work together to perform a specific function ex. Heart = nerve, blood & muscle tissue

LEVELS OF ORGANIZATION

Body systems are made up of organs that work together

ex. digestive = esophagus – stomach - small intestine - large intestine - rectum

ex. circulatory, respiratory, nervous

Organisms are made up of body systems that work together for life

ex. you, paramecium, frog, trees

Scientific Method

• Science: a way of studying the world in order to understand how it works.

• Biology: the study of living things– Biology is used in medicine, veterinary

sciences, ecology, and genetics.– Biological knowledge is used to fight diseases

such as the flu, pneumonia, and AIDS

Science is a search for knowledge

• Science is used to solve problems that affect our lives.

• Hypothesis: a testable explanation for an observation

• Prediction: what you expect to happen IF your hypothesis is correct

• The controlled test of a hypothesis is called an experiment.

• In a CONTROL EXPERIMENT, a group that HAS NOT been exposed to the variable causing an effect is compared to a group that HAS BEEN exposed to the variable.

• The group NOT exposed to the variable is called the CONTROL GROUP.

• The VARIABLE is the factor you are testing that causes some effect.

• Theory: a unifying explanation for a broad range of observations – generally accepted as true.

• Science requires continued verification of hypothesis

• All Scientific theories can be overturned by new evidence.

SCIENTIFIC METHOD• The scientific Method is a systematic study of a question or

problem. 7 steps1. State the Problem2. Observations3. Gather Data4. Hypothesis5. Experiment6. Analyze data7. Draw a Conclusion8. **Repeat to ensure there were no mistakes**

Biochemistry

Elements and Atoms• Matter is anything that has mass and takes up space.• Atoms are the basic building blocks of all matter.• Elements are basic substances that cannot be broken

down into other substances.• Molecules are formed by the joining of atoms of two

or more elements. (smallest combination that cannot be divided without changing its chemical and physical properties)

• Compounds are composed of atoms of different elements chemically combined.

Atoms

• Atom consists of three subatomic particles called:Protons: positive chargeNeutrons: neutral/no chargeElectrons: negative charge

• The center of an atom is called the nucleus which consists of protons and neutrons.

Organic Substances/components

• Carbohydrates: made up of simple sugars• Proteins: made up of amino acids • Lipids: made up of a glycerol and at least 1

fatty acid• Nucleic Acids: made up of nucleotides

Organic Substances – contain Carbon and Hydrogen

Enzymes

• Enzymes are proteins that are used by the cell to speed up and regulate metabolic reactions.

• Enzymes are biological catalysts that remain unchanged by the reaction.

Organic SubstancesCarbohydrate

sProteins Lipids Nucleic Acids

SugarsStarches

MeatsHormones

MuscleHairNails

EnzymesBlood Cells

FatsOils

Waxes

DNARNA

Viruses!

Viruses are microscopic particles that invade the cells of plant, animals, fungi, and bacteria.

Bacteriaphage AIDS Virus

1. A virus is not a cell. A typical virus is composed of a core of genetic material surrounded by a protein coat. The protein coat protects the virus and enables it to invade its host cell.

2. In many viruses, DNA is the genetic material. Other viruses have RNA.

3. Viruses are parasitic and can reproduce only inside the cells of their host. This makes viruses very different from bacteria and protists.

AIDS Virus

In the Lysogenic Cycle:

1. Viral DNA merges with Cell DNA and does not destroy the cell. 2. The Virus does not produce progeny. 3. There are no symptoms of viral infection. 4. Temperate viral replication takes place.

Differences Between Lytic and Lysogenic Cycles

In the Lytic Cycle:

1. Viral DNA destroys Cell DNA, takes over cell functions and destroys the cell.

2. The Virus replicates and produces progeny phages. 3. There are symptoms of viral infection. 4. Virulant viral infection takes place.

•Some bacteria are autotrophs. •Autotrophic organisms make their own food by using simple molecules.

Autotrophs and Heterotrophs

•Most bacteria cannot make their own food and are therefore heterotrophs. •Many feed on dead animals and animal wastes; dead plants; and fallen leaves, branches, and fruit.

PHOTOSYNTHESIS/CELLULAR RESPIRATION

Energy in Living Systems

I. All organisms need energy I. The sun is the first and largest source of energy

II. Autotrophs

I. Organisms that gather their own energy

III. Heterotrophs

I. Organisms that gather energy from other organisms

Photosynthesis –Sun Energy

• Photosynthesis– In the chloroplasts

• Steps– Absorption of Light

• Energy is captured from the sunlight– Electron Transport Chain

• Light energy is converted to chemical energy ATP– Calvin Cycle

• ATP powers the formation of organic compounds

Photosynthesis:Energy from the Sun

Cellular EnergyI. Energy from food is trapped in ATP

I. Aerobic reactionI. Need Oxygen

II. Anaerobic reaction

I. Oxygen is not needed II. In Mitochondria

III. Plant and Animal Cells

C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy

Cellular Respiration: Energy from food!!

Movement of Molecules

Osmosis

Passive TransportI. Requires NO energy

I. DiffusionI. Molecules move from HIGH concentration

to LOW concentration.

Passive Transport

II. OsmosisI. Diffusion of water across a biological membraneII. Helps cell maintain homeostasis

I. Maintaining stable conditionIII. Three examples:

Isotonic Solution[Water in] = [Water out] Cell is Happy

Hypotonic Solution[Water in] < [Water out] cell swells and blows up

Hypertonic Solution[Water in] > [Water Out] Cell Shrinks

Active TransportI. Requires Energy (ATP)

I. Some molecules are not easily diffused across membrane

II. Proteins embedded in membrane are used

Transport of Large Stuff

I. EndocytosisI. Cell takes “in” materials

II. ExocytosisI. Expulsion of material “out” of cell

Endocytosis

Exocytosis

41

Cellular Division

42

DNA ReplicationDNA must be

copied or replicated before cell division

Each new cell will then have an identical copy of the DNA

Original DNA strand

Two new, identical DNA strands

43

KaryotypeA picture of the

chromosomes from a human cell arranged in pairs by size

First 22 pairs are called autosomes

Last pair are the sex chromosomes

XX female or XY male

44

Abnormal Karyotype• Karyotypes can be used to examine an individual’s chromosomes and identify possible abnormalities in chromosome number.

• There should be only two copies of the #21 chromosome

• Instead there are three– This called trisomy/(non-

disjunction)– This occurs when

chromosomes in sex cells do not separate properly. Individuals with this abnormality do not develop properly

45

Five Phases of the Cell Cycle

G1 - primary growth phaseS – synthesis; DNA

replicatedG2 - secondary growth

phasecollectively these 3 stages are called interphase

M - mitosisC - cytokinesis

46

Four Mitotic Stages

ProphaseMetaphaseAnaphaseTelophase

47

CytokinesisCleavage furrow in animal cell

Cell plate in plant cell

48

Facts About Meiosis

Daughter cells contain half the number of chromosomes as the original cell

Produces gametes (eggs & sperm)

Occurs in the testes in males (Spermatogenesis)

Occurs in the ovaries in females (Oogenesis)

49

Start with 46 double stranded

chromosomes (2n)After 1 division - 23 double stranded chromosomes (n)After 2nd division - 23 single stranded chromosomes (n)

  Occurs in our germ cells that produce gametes

More Meiosis Facts

DNA & RNA

Parts and What-not

DNA/ RNA Notes•DNA- deoxyribonucleic acid, the material that contains the information that determines inherited characteristics.

I. Found: inside the nucleus of a cellII. Job: makes proteinsIII. Structure: double helix- two strands twisted around each other like a spiral staircase.IV. Nucleotides: subunits that make up DNA

A. There are 3 parts to each Nucleotide1. Phosphate group2. 5- carbon sugar molecule3. Nitrogenous base group

Adenine (A) Guanine (G) Thymine (T) Cytosine (C)

4. Chargaff< A=T , G=C•DNA Replication- Replication results in two identical DNA strands (p. 198)

A. The two original DNA strands separateB. DNA polymerases add complementary nucleotides to each strandC. Two DNA molecules from that are identical to the original DNA molecule.

•RNA- ribonucleic acid- present in all living cells and plays a role in protein synthesisI. Different than DNA in 3 ways

A. single strand of nucleotidesB. sugar is Ribose ( in DNA its DeoxyriboseC. Like DNA it has 4 bases

1. Adenine (A)2. Guanine (G)3. Cytosine (C)4. Uracil (U) – This Takes the place of Thymine (T)5. A=U , G=C

II. There are 3 types of RNAA. mRNA- messenger RNA- carries instructions for making proteins out of the nucleus to the site of TranslationB. tRNA- transfer RNA- helps translate the mRNA’s message so that amino acids can be made to construct the proper proteinC. rRNA – ribosomal RNA-helps tRna translate the mRNA’s message.

From Genes to ProteinsAll About RNA

Transcription

• Takes place in the nucleus.• Starts at a ‘start’ signal and ends with a ‘stop’

signal.• Requires RNA polymerase

– Opens DNA– Adds complementary nucleotides of RNA

•mRNA then leaves through the nuclear pores out to the cytoplasm where it settles on a ribosome.

Genetic Code

• The instructions for making proteins are written as a series of three-nucleotide sequences on the mRNA called codons.

• Each codon codes for an amino acid or signals a start or stop for translation.

• AUG = start• UAG = stop

Translation• Takes place in the cytoplasm on the

ribosomes.• tRNA molecules are single strands of RNA that

temporarily carry an amino acid on one end.• Each tRNA contains an anticodon for the

mRNA’s codon.• The anticodon is a three-nucleotide sequence

that is complementary to a particular mRNA codon.

Translation continues…

• When a tRNA’s anticodon matches up with the codon of mRNA, it drops off its’ amino acid.

• Each amino acid forms a peptide bond with the previous amino acid which results in the production of a protein.