BIOLOGY

MIDTERM EXAM REVIEW

The Science of Life

Biology is the science of LIFE.Life:•Organisms are made from and develop from cells!– Unicellular (one cell)– Multicellular (many cells)

• Cells of multicellular organisms undergo differentiation.

The Science of Life

Cell differentiation is a process in which a non-specific cell develops into a specific type of cell in response to specific

triggers from the body or the cell itself.

The Science of Life

Biology is the science of LIFE.Life:•All living things maintain stable internal conditions know as homeostasis!•All organisms reproduce – they pass down their genetic information to offspring through DNA.– Sexual reproduction– Asexual reproduction

The Science of Life

Asexual reproduction 1. Binary Fission (prokaryotes)

2. Mitosis (eukaryotes)

•Results in identical cells, or clones of the parents!!

Sexual reproduction 1. Meiosis (eukaryotes)

– Results in gametes - sex cells (sperm and egg)– Cuts chromosomes in half– Adds genetic variety!!

Reproduction: the production of offspring by a sexual or asexual process.

The Science of Life

Biology is the science of LIFE.Characteristics of Life:•Populations of organisms evolve or change over time.•All organisms interact with their living and non-living environment.

• Ecology – branch of biology that studies these interactions.

Cont.

The Science of Life

•All living things must obtain energy.• Heterotrophs – organisms that must obtain their

energy from ingesting other organisms

• Autotrophs – organisms that can obtain their energy by producing their own food

Photosynthesis and Cellular Respiration

The Science of Life

SCIENTIFIC METHOD:How Scientists solve a problem or

answer a question…

ObservingAsking a Questio

n

Collecting Data

HypothesizingExperimen

tingDrawing

Conclusions

The Science of Life

The Science of Life

SI Measurements

Length Mass Volume

Chemistry

•Everything in the universe is made of matter.•Everything in the universe has mass.

Chemistry

Elements are pure substances that can not be broken down into

simpler kinds of matter

Chemistry

An Atom is the simplest particle of an element.

Chemistry

Atoms are held together by bondsCovalent Bonds

Ionic Bonds

Chemistry

Energy & MatterStates of Matter:

Chemistry

Chemical Reactions:

Energy is absorbed

Energy is Released

Chemistry

Solutions:

Water is theuniversal solvent

Chemistry

Acids and BasesAcid: 0 - 6.5 Base: 7.5 - 14

Neutral – 7.0

Chemistry

Properties of Water

Capillarity

BIOCHEMISTRY

The Building Blocks of Life:

Four types of macromolecules(large, carbon-based organic molecules)

are found in living organisms.

The Element of Life

BIOCHEMISTRY

The Building Blocks of Life:Organic Molecules, Macromolecules, Biomolecules

The Molecules of Life:Most are polymers—chains of smaller

molecules (monomers) that form through dehydration synthesis.

(the loss or removal of a water molecule).

CARBOHYDRATESNucleic AcidsLIPIDS

PROTEINS

BIOCHEMISTRYCarbohydrates:

•Energy-storing molecules containing carbon, hydrogen, and oxygen in a 1:2:1 ratio.

•Monosaccharides, such as glucose (C6H12O6), are single-sugar subunits (monomers) often found as rings.•Disaccharides have two monosaccharide subunits•Polysaccharides, such as starch (plant storage), glycogen (animal storage), and cellulose (plant fiber), are long chains of sugars.

BIOCHEMISTRY

Lipids:Most Lipids are composed of fatty acids

All lipids are hydrophobic - (insoluble in water or water ‘hating’).

There are three main families of lipids:Fats, Oils & Waxes, Steroids and

Phospholipids

BIOCHEMISTRY

FATS & OILS:•Large, HIGH energy-storing molecules, each built from two components:– One molecule of glycerol, a three-carbon alcohol.– Three fatty acids, long hydrocarbon chains that

attach to the glycerol backbone. • (Hence, fats are also called triglycerides.)

BIOCHEMISTRY

Steroids: Four fused-hydrocarbon rings, such as cholesterol.

Phospholipids: Glycerol with two fatty acids and a phosphate group attached (found in cell membranes).

BIOCHEMISTRY

PROTIENSLong polymer chains called polypeptides

built from single amino acids linked together by peptide bonds.

BIOCHEMISTRY

PROTIENS

Every amino acid contains a central carbon with an amino group (NH2), a carboxyl group

(COOH), hydrogen (H), and one of 20 side groups (R) that makes each amino acid

different.

BIOCHEMISTRY

ENZYMES:Enzymes are proteinscapable of speedingchemical reactions without being consumed (used).

Enzymes lower the amount of energy needed to start a reaction.

The substrate binds to the enzyme’s active site in an induced fit, in which the enzyme changes its shape to wrap itself around the substrate.

BIOCHEMISTRY

ENZYMES:

Enzymes have a variety of functions in the body, including:•digesting food•Transmitting nerve impulses•making our muscles work.

BIOCHEMISTRY

NUCLEIC ACIDS:

Polymers of nucleotides that encode genetic information.

There are two forms:deoxyribonucleic acid (DNA) and ribonucleic

acid (RNA).

BIOCHEMISTRYNUCLEIC ACIDS:

Individual nucleotides are linked by phosphate bonds and contain

three basic parts:*Phosphate group, *5 carbon sugar

(deoxyribose or ribose) and a nitrogenous base.

BIOCHEMISTRYNUCLEIC ACIDS:

The double helix (double strand) is formed from weak hydrogen bonds between complementary

nitrogenous bases (adenine and thymine; guanine and cytosine) on opposite strands of a the DNA

molecule.

BIOCHEMISTRYNUCLEIC ACIDS:

Complementary Base Pairing:In DNA, nitrogenous base Adenine always pairs with Thymine;Cytosine always pairs with Guanine

Bases A, G, T, C

BIOCHEMISTRY

DNA

Coiled DNA

Coiled DNA as

Chromosom

es in

nucleus

Structure & Functionof the Cell

THE CELL THEORY1. Every living organism is made up of cells

2. Cells are the lowest level of structure capable of performing all the activities of life.

3. All cells arise frompreexisting cells.

Structure & Functionof the Cell

•Not all cells are alike•Cells are limited in size by the ration between their surface area and volume•A cellsshape determinesits function

TYPES OF CELLSProkaryotic Cells – simple cell, no membrane bound nucleus (only nucleoid region with DNA) or no membrane bound organelles (i.e no mitochondria, golgi body, etc. but have ribosomes)

Eukaryotic Cells – more complex cell, membrane bound nucleus (DNA containing) and organelles.

Animal Cell & Plant Cell (Eukaryotic)Bacteria Cell (Prokaryotic)

TYPES OF CELLS

CELL MEMBRANECell membrane:

Serves as an external barrier and encloses organelles.

The basic unit of the cell membrane is the phospholipid bi-layer molecule

Cell membranes are semipermeable, allowing passage of gases (O2 & CO2), lipids, and small polar molecules but not charged molecules (ions and proteins) or large polar molecules without the use of ENERGY (ATP).

CELL MEMBRANE

Membrane proteins embedded in the bilayer help transport molecules unable to cross the

membrane independently

TYPES OF CELLS

Cells of Eukaryotes:Eukaryotes include multicellular plants and animals, fungi and some unicellular protists.Their cells contain membrane-bound organelles, each of which performs specific functions.

TYPES OF CELLS

Nucleus: Membrane-bound storage site of genetic information that determines heredity and directs the activities of a cell.

Mitochondria: Membrane bound Power plant of the cell and the location of aerobic respiration.

TYPES OF CELLS

Smooth/rough endoplasmic reticulum (SER/RER): Network of membranes where lipids and proteins are synthesized.Rough ER is covered with ribosomes.

Golgi apparatus: Organelle that packages and exports proteins and lipids produced in the ER.

TYPES OF CELLS

Vesicles: Sacs in which substances are transported or stored.

Lysosomes: Vesicles of digestive enzymes that degrade old cellular components.

TYPES OF CELLS

Plant cells contain several additional components:

Chloroplasts: Sites of photosynthesis. Contain chlorophyll (a green pigment)and have a double membrane.

Vacuole: Vesicle used to store water, proteins, and wastes.

Cell wall: Rigid cellulose layer around the cell membrane.

ORGANELLES

TYPES OF CELLS

Cells of Prokaryotes:

Prokaryotes include the simplest unicellular organisms and were the earliest cells to

evolve (bacteria).

**Major differences from eukaryotes**

– Genetic material (DNA) floats in the cytoplasm in a concentrated but unbounded region called the nucleoid.

– There are no membrane-bound organelles.

TYPES OF CELLS

CELL REPRODUCTION

DNA is the cell’s genetic material; chromosomes are the carriers of this genetic information.

In prokaryotes, the chromosome is a single circle of DNA.

In eukaryotes, each chromosome is a complex of DNA and proteins found in the nucleus.

CELL REPRODUCTION

Prokaryotic cells reproduce via binary fission (asexual). In this process, DNA is replicated, and the cell splits in two roughly equal parts, each with a copy of the cell’s DNA.

Eukaryotic cells reproduce sexually via the creation of two identical diploid cells from one diploid cell. Diploid (2N) refers to the total number of chromosomes in autosomal cells.

HOMESTASIS & TRANSPORT

Diffusion & Passive Transport

(Require No Energy):

Molecules move freely across a membrane to balance a

concentration gradient, from areas of high to low

concentration.

Diffusion of water is called osmosis.

HOMESTASIS & TRANSPORT

Osmosis is the diffusion of water across a membrane. Like other molecules, water will move from an area of high concentration to an area of low concentration

(depends on the environment surrounding

cell).

•Hypertonic - Solution that has a higher concentration of solute and a lower concentration of water than the cell. •Hypotonic - Solution that has a lower concentration of solute and a higher concentration of water than the cell.

Water Water

Water

HOMESTASIS & TRANSPORT

Diffusion & Passive Transport

(Require No Energy):

Facilitated diffusion: Molecules cross an

impermeable or semipermeable membrane down their concentration

gradient but must do so via special channels.

HOMESTASIS & TRANSPORT

Active transport (Require Energy)Transport of molecules from areas of low to high

concentrations across a membrane using anEnergy-dependent transport protein.

•Endocytosis: Enveloping of an exterior substance within a membranous vesicle for admission to the cell interior.– Pinocytosis: Endocytosis of dissolved liquid molecules.– Phagocytosis: Endocytosis of undissolved solid matter.

•Exocytosis: Extrusion of material from a cell by discharge from vesicles at the cell surface.

ATP

HOMESTASIS & TRANSPORT

.

Energy

CLASSIFICATION

To study so many life-forms, biologists have organized them into numerous

groups based on their similar characteristics.

Classifying and naming organisms is key to distinguishing, describing and

understanding the relationships between living and non-living (extinct)

organisms.

The branch of biology that deals with classification of life-forms is known as

taxonomy.

CLASSIFICATION

In response to the need for better organization, an 18th century Swedish botanist named

Carolus Linnaeus offered a solution to the confusion of classifying and naming organisms.

Linnaeus’s classified animals based on their similarities in morphology (form & structure),

rather than by location.(i.e. bats have wings but are not birds)

CLASSIFICATION

Carolus Linnaeus’s Classification System:

There are two important features of this system:

1.The system classifies species into hierarchical levels, in which level is nested within larger levels (taxa).

2.Each species has a two-part name.

CLASSIFICATION

Part 1 - Seven Levels (taxa) of Classification

Keep Plates Clean Or Family Gets Sick!

KingdomPhylum

ClassOrder

FamilyGenus

Species

Least Specific or Broadest Taxon

Most Specific Taxon

CLASSIFICATION

Domestic Dog

CLASSIFICATION

Part 2 - Binominal Nomenclature

The two-part name Linnaeus gave each organism is a Latin, scientific name.

Genus, species = Panthera leo

CLASSIFICATION

Biologists have developed a precise method to help them classify and identify unknown

organisms.

The classification tool called a dichotomous key, uses a logical approach

to classify an organism.

CLASSIFICATION

The Six Kingdom System:

CLASSIFICATION

IMPO

RTANT

!!

CLASSIFICATION

The New Three Domain System

THE CONTROLLED EXPERIMENT

Most experiments in Biology are controlled experiments - Used to gather data under controlled conditions.

– performed to test your hypothesis(an educated guess) (prove or disprove it)

– Based on a comparison of a control group with an experimental group.Group not

exposed to

the

experiment

al conditio

ns -

can be

given a

placebo

Group that IS exposed to the experimental conditions – or the independent variable

THE CONTROLLED EXPERIMENT

All factors in the control group and the experimental group are identical except for one:• independent variable - what is being

testedDuring the experiment, observations and measurements are taken from both groups, looking specifically at another factor or variable:• dependent variable - dependent because

it is driven by/or results from the independent variable.

IMPO

RTANT

!!

MIDTERM REVIEWCOMPLETE