Biology Final Review

Chromosomes

• Chromosomes are DNA & its associated proteins. We have 46 chromosomes or 23

pairs of chromosomes.

• In a prokaryotic cell, it is the main ring of DNA.

Autosomes vs. Sex Chromosomes

• Autosomes are any chromosomes that are not directly involved in determining the sex of an individual.

We have 22 pairs.

• Sex chromosomes contain genes that will determine the sex of the individual.

We have one pair. Females are XX. Males are XY.

Autosomes vs. Sex Chromosomes

Gametes

• Gametes are an organism’s reproductive cells. Female’s gametes are eggs or ova. Male’s gametes are sperm.

Haploid vs. Diploid

• Haploid refers to a cell (gamete) that contains only 1 set of chromosomes.

It is represented by “n.”

• Diploid refers to a somatic or body cell that contains 2 sets of chromosomes.

It is represented by “2n.”

Define Haploid

• Describes a cell, nucleus or organism that has only one set of unpaired chromosomes.

Define Diploid

• A cell that contains 2 sets of haploid chromosomes

• Body or somatic cells contain a diploid number of chromosomes.

Karyotype

• A picture of the chromosomes found in an individual’s cells at metaphase of mitosis & arranged in homologous pairs & in order of diminishing size with the sex chromosomes last.

• Down’s Syndrome

is trisomy 21.

Parts of a Microscope

Microscopes and Magnification

• Ocular lens x objective lens = total magnification

• Magnification – making image appear larger

• Resolution – clarity of image

Cell Theory

• All living things are made of cells.

• Cells are the basic units of structure and function in organisms.

• All cells come from existing cells.

Prokaryote vs. Eukaryote

• Prokaryote No nucleus No membrane bound organelles Circular DNA Relatively small Reproduce quickly (20 min.)

Examples: Bacteria

Prokaryote vs. Eukaryote

• Eukaryote Nucleus Many membrane bound organelles Linear DNA Relatively large Reproduce slowly (24+ hours)

Examples: Plants, animals, fungi & protists

Cell Parts & Functions

• Cell membrane Controls what enters & leaves a cell;

separates & protects the cell from the environment.

• Nucleus Contains the DNA in eukaryotic cells;

controls cellular activities.

• Vacuole Membrane bound sac that stores water, may

also contain ions, nutrients & waste.

Cell Parts & Functions

• Chloroplast Organelle that uses light energy to make

carbohydrates from CO2 & H2O.

• Cytoplasm Region of the cell within the membrane that

includes the fluid, the cytoskeleton and all of the organelles except the nucleus.

• DNA Material that contains the information that

determines hereditary characteristics.

Cell Parts & Functions

• Ribosomes Organelle composed of RNA & protein; site

of protein synthesis.

• Mitochondrion Cell organelle surrounded by 2 membranes &

is the site of cellular respiration, which produces ATP.

• Cell Wall Rigid structure that surrounds the cell

membrane & provides support to the cell.

5 Stages of the Cell Cycle

5 Stages of the Cell Cycle

• The first 3 stages are collectively called interphase. (90% of a cell’s life is spent here.)

1. First growth (G1) phase Cell grows rapidly & carries out

routine functions. (Major portion of a cell’s life is spent here.)

5 Stages of the Cell Cycle

2. Synthesis (S) phase Cell’s DNA is copied. Each chromosome consists of 2 chromatids

attached at the centromere.

3. Second growth (G2) phase Preparations are made for the nucleus to

divide. Microtubules are rearranged. Organelles are manufactured or reproduced.

5 Stages of the Cell Cycle

4. Mitosis The nucleus of a cell divides into 2

nuclei each with the same # and kinds of chromosomes as the original cell.

5. Cytokinesis The cytoplasm divides and 2 new cells

are formed.

3 Checkpoints

• A checkpoint is an inspection point at which feedback signals from the cell can trigger the next phase of the cell cycle or delay it.

1. Cell Growth (G1) checkpoint at the end

of the G1 phase Makes the decision of whether or not a

cell will divide.

3 Checkpoints

2. DNA synthesis (G2) checkpoint at the

end of the G2 phase DNA replication is checked by DNA

repair enzymes.

3. Mitosis checkpoint at the end of mitosis Triggers the exit from mitosis

4 Phases of Mitosis

1. Prophase Chromosomes become

visible. Nuclear envelope

dissolves. The spindle forms. In animal cells, the

centrioles move to opposite poles and the spindle forms between them.

4 Phases of Mitosis

2. Metaphase Chromosomes

move to the center of the cell & line up along the equator.

Spindle fibers link the chromatids of each chromosome to opposite poles.

4 Phases of Mitosis

3. Anaphase Centromeres divide. The 2 chromatids

(now called chromosomes) move toward opposite poles as the spindle fibers attached to them shorten.

4 Phases of Mitosis

4. Telophase A nuclear envelope

forms around the chromosomes at each pole.

The chromosomes uncoil and return to chromatin form.

The spindle dissolves.

Cytokinesis begins.

Cytokinesis

• Division of the cytoplasm of a cell• Follows the division of the cell’s nucleus by

mitosis or meiosis• Cytokinesis in animal cells occurs when a

belt of protein threads pinches the cell membrane in half.

• Cytokinesis in plant cells occurs when vesicles from the Golgi apparatus fuse to form a cell plate.

Cytokinesis

• Cytokinesis in Cytokinesis in

animal cells plant cells

Define Meiosis• A process in cell division during which the number

of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells (gametes or spores)

What are the 4 things that give rise to variation within a species?

• Independent assortment

• Crossing-over

• Random fertilization

• Mutations

Differentiate between spermatogenesis & oogenesis.

• Spermatogenesis2 nuclear

divisions in which the cytoplasm is divided equally

4 sperm produced from parent cell

Differentiate between spermatogenesis & oogenesis.

• OogenesisFirst nuclear division,

cytoplasm divides unequally – one of the cells gets nearly all of the cytoplasm

This cell will ultimately give rise to one egg – the 3 polar bodies will die

Complete the following diagrams

Process: Mitosis

Process: Meiosis

2n2n

2n

Compare Mitosis and Meiosis

What are the 3 different ways asexual reproduction occurs?• In asexual reproduction, a single parent

passes exact copies of all of its DNA to its offspring.

• Fission

• Fragmentation

• Budding

Nondisjunction

• One or more chromosomes fail to separate properly during meiosis.

• One gamete ends up receiving both chromosomes and the other gamete receives none.

• Trisomy occurs when the gamete w/ both chromosomes fuses w/ a normal gamete, resulting in an offspring w/ 3 copies of a chromosome instead of 2.

Diffusion vs. Osmosis

• Diffusion The movement of particles from regions of

higher concentration to regions of lower concentration.

Ex: perfume spreading across a room.

• Osmosis The diffusion of water from an area of high

concentration to an area of low concentration across a membrane.

Ex: Getting thirstier when you drink salt water.

Passive vs. Active Transport

• Passive Transport Does not require energy. Movement down the concentration

gradient. Examples:

Diffusion Osmosis Facilitated diffusion

Passive vs. Active Transport

• Active Transport Requires energy. Movement against the concentration gradient. Examples:

Sodium-potassium pump Endocytosis

Phagocytosis Pinocytosis

Exocytosis

Fig. 5-1a

Cholesterol

Glycoprotein

Glycolipid

Carbohydrate ofglycoprotein

Phospholipid

Microfilamentsof cytoskeleton

Integrin

ATP

• The energy “currency” of the cell.• An organic molecule that acts as the

main energy source for cell processes• Composed of a nitrogen base, a sugar

& 3 phosphate groups. • The energy is stored in the phosphate

bonds.• Powers metabolism.

Photosynthesis

• Process by which plants, algae & some bacteria use sunlight, CO2 &

H2O to produce carbohydrates & O2.

• Takes place in the chloroplast

• Main pigment is chlorophyll.

• Reactants are CO2 and H2O

• End products are glucose & O2

Photosynthesis

• Stage 1 Consists of the absorption of light

energy which excites the electrons in chlorophyll.

The electrons enter the ETC (electron transport chain).

Water is split to produce O2, H+, and

the electrons to replace those lost by the chlorophyll molecules.

Photosynthesis

• Stage 2 The conversion of light energy into

chemical energy that is temporarily stored in ATP and NADPH.

The energy from ATP and NADPH will be used to power the third stage.

Photosynthesis

• Stage 3 CO2 fixation occurs

Inorganic CO2 is fixed into organic

compounds (sugars).

Cellular Respiration

• Process by which cells produce energy from carbohydrates; O2

combines w/ glucose to form H2O &

CO2.

• Takes place in the mitochondrion.

• Reactants are glucose and oxygen.

• Products are carbon dioxide & water.

Aerobic Respiration vs. Anaerobic Respiration

• Aerobic Respiration Requires oxygen. Produces much more ATP (38 net ATP)

• Anaerobic Respiration Does not require oxygen. Regenerates NAD+ so that gylcolysis can

continue. (2 net ATP from glycolysis)

Aerobic Respiration

• Stage 1 – Glycolysis takes place in the cytoplasm.

Does not require oxygen. Glucose is broken down to 2 pyruvate

molecules Produces 2 net ATP and 2 NADH

• Stage 2 – Bridge reaction carries pyruvates into the mitochondrion.

2 CO2 and 2 NADH are produced

Aerobic Respiration

• Stage 3 – Krebs Cycle occurs in the matrix of the mitochondrion

In the presence of oxygen. In two turns of the Krebs Cycle:

4 CO2 are produced

6 NADH are produced 2 ATP are produced

2 FADH2 are produced.

Aerobic Respiration

• Stage 4 – Electron Transport Chain occurs in the inner membrane of the mitochondrion

In the presence of oxygen. 34 net ATP produced

2NADH from glycolysis = 6ATP 2 NADH from bridge reaction = 6 ATP 6 NADH from Krebs cycle = 18 ATP 2 FADH2 from Krebs cycle = 4ATP

Anaerobic Respiration or Fermentation

• Alcoholic Fermentation Occurs in the absence of oxygen Occurs in yeast and some bacteria Produces:

Ethyl alcohol Carbon dioxide Regenerates NAD+ so glycolysis can

continue

Anaerobic Respiration or Fermentation

• Lactic Acid Fermentation Occurs in the absence of oxygen Occurs in the muscle tissue of animals

& in lactic acid bacteria Produces:

Lactic acid Regenerates NAD+ so glycolysis can

continue

Atom and Its Parts

• An atom is the smallest unit of an element that maintains the properties of that element.

Nucleus contains: Proton (+) Neutron (Neutral)

Electron cloud Electron (–)

Covalent vs. Ionic Bonds

• Covalent Bond Bond formed when atoms share pairs of

electrons.

• Ionic Bond Bond formed by the attraction between

oppositely charged ions.

Covalent vs. Ionic Bonds

Molecules and Polar Molecules

• Molecule A group of atoms held together by

covalent bonds.

• Polar Molecule Shares its electrons unequally and

therefore has partially positive and negative ends, or poles.

Water is a polar molecule.

Molecules and Polar Molecules

Solvents

• Solvent A substance, usually a liquid,

capable of dissolving another substance.

• Universal Solvent Water.

pH Scale and Acids & Bases• pH Scale ranges from 0 - 14

Acid A compound that forms hydrogen ions (H+) in water. Its pH is 0 to less than 7. (0 to < 7)

Base A compound that forms hydroxide ions (OH-) in water. Its pH is greater than 7 to 14. (>7 to 14)

Neutral Substances that have a pH of 7.

Organic Macromolecules

• Organic macromolecules: Contain carbon atoms that are covalently

bonded to other elements – typically hydrogen, oxygen and other carbon atoms.

4 principal classes of organic compounds found in living things are: Carbohydrates Lipids Proteins Nucleic acids

Organic Macromolecules

• Carbohydrates – organic compounds made of carbon, hydrogen and oxygen in a 1:2:1 ratio.

Monomers are monosaccharides. Ex: Glucose and fructose

Polymers are polysaccharides. Ex: Starches, potatoes, paper, crab shells

Functions Stores energy. Makes up cell walls in plants and fungi. Makes up exoskeleton in some animals.

Organic Macromolecules• Lipids are nonpolar molecules that are

insoluble in water & include fats, phospholipids, steroids and waxes.

Monomers are glycerol & fatty acids Polymer examples

Butter & oil All membranes Cholesterol and Steroids

Functions Stores energy Makes up cell membranes Acts as chemical messengers

Organic Macromolecules• Proteins

Monomers are amino acids Polymer examples

Hemoglobin and antibodies Muscle, hair and nails

Functions Hemoglobin carries oxygen and antibodies help

defend against infection. Make up tissues that support body structures and

provide movement Speed up chemical reactions (enzymes)

Organic Macromolecules• Nucleic acids

Monomers are nucleotides Polymer examples

DNA RNA

Functions Controls cellular activities Stores hereditary information Plays key role in the manufacture of

proteins

Catalyst vs. Enzyme

• Catalyst Speeds up chemical reactions by

lowering the activation energy.

• Enzyme Specialized protein that acts as an

organic catalyst.

Test Indicators & Positive Results

• Benedict’s solution Tests for simple sugars – blue color changes

to red, orange, yellow, green.

• Lugol’s iodine Tests for starch – reddish–orange iodine turns

blue-black or black.

• Biuret solution Tests for protein – blue turns purple.

• BTB (Bromthymol blue) Tests for CO2 – blue turns green, or yellow.