BIOLOGY CLEP NOTES

Matter

Anything that takes up space and has mass, made of elements.

Elements

Substances that cannot be broken down into other substances.

Atoms

The smallest unit of matter, composed of neutrons, electrons (-), and protons (+).

Compound

Two or more different elements combined in a fixed ratio.

Molecule

Two or more same or different elements combined in a fixed ratio.

Electrons

Negatively charged particles found orbiting in shells around the nucleus of an atom.

Valence shell

The outermost shell of an atom that contains valence electrons.

Chemical Bonds

Attractions that keep atoms close together.

Covalent Bonds

Bonds formed by the sharing of a pair of electrons between atoms.

Polar Covalent Bonds

non equal sharing

Non-polar Covalent Bonds

equal sharing

Ionic Bonds

Bonds formed when an anion steals an electron from a cation.

Hydrogen bonds

Weak bonds formed between the poles of hydrogen and oxygen in water molecules.

Chemical Reactions

Processes that make and break chemical bonds.

Reactants

Substances that start a chemical reaction.

Products

Substances produced at the end of a chemical reaction.

Endothermic

Reactions that absorb energy.

Exothermic

Reactions that release energy (ex bombs)

Properties of water

- Only molecule that exists in all three states

- Solid is less dense than liquid (ice floats)

- Adhesion – sticks to other molecules well

- Cohesion – sticks to itself well

- Surface tension – difficult to break the surface

- Universal solvent – just about everything dissolves in it

- High specific heat – longer to increase temperature

- Evaporative cooling

Acids

Substances that dissolve in water and increase the hydrogen ion concentration in the solution.

Bases

Substances that dissolve in water and decrease the hydrogen ion concentration in the solution.

pH scale

A scale used to measure the acidity or basicity of a solution.

Organic Molecules

Molecules containing carbon.

Carbohydrates

Organic molecules made up of carbon, oxygen, and hydrogen.

• Monosaccharide – monomer (ex glucose)

• Polysaccharide – polymer (ex starch)

Lipids

Hydrophobic organic molecules

• Waxes – form water barriers

• Fats – energy storage

• Phospholipids – cell membranes

• Steroids - hormones

Proteins

Organic molecules made up of amino acids.

• enzymes

• defense (antibodies)

• muscle

Nucleic Acids

Organic molecules used for information storage made of nucleotides

Nucleotide makeup

o   1 Nitrogen base – (joint by hydrogen bonds)

• Adenine (A)

• Thymine (T) – DNA only

• Uracil (U) – RNA only

• Cytosine (C)

• Guanine (G)

o   Pairs - A & T/U and C&G

o   1 Sugar

• Deoxyribose – DNA

• Ribose - RNA

o   1 Phosphate group (backbone squiggle)

Cells

The smallest units of living things.

Cell Organelles

Structures within a cell that perform specific functions.

Cytoplasm

• the goo

• jelly like substance where organelles are suspended

Cell Membrane

The lipid layer surrounding a cell.

Nucleus

The command center of a cell that stores and protects most of the DNA. Makes RNA and ribosomes

Ribosomes

Protein factories that use DNA instructions to create proteins.

Endoplasmic Reticulum

An organelle involved in lipid synthesis, detoxification, and protein production.

Golgi Apparatus

An organelle involved in receiving, sorting, and modifying proteins.

This is the shipping center for the ER

Mitochondria

Organelles involved in cell respiration and energy production.

Converts FOOD to energy

Chloroplasts

Organelles involved in photosynthesis.

converts LIGHT to energy

Cytoskeleton

A network of protein fibers that provide structure and support to cells.

Cell Wall

A rigid structural support found in plants, bacteria, prokaryotes, and fungi.

Membranes

Boundaries between the inside of a cell and its surroundings.

Hypo-tonic

cell loses water

Phospholipid bilayer

o   White outside part is the hydrophilic part that likes to interact with water

o   Yellow inner is hydrophobic which doesn’t like water

Passive Transport

Diffusion across the membrane without the use of energy.

Sometimes needs a doorway protein to get through

Diffusion

each molecule moves random from higher to lower concentration (no energy) (think perfume)

Osmosis

diffusion of water (higher to lower concentration)

Facilitated Diffusion

diffusion with a doorway (protein that only allows certain proteins)

Active Transport

Transport that requires energy and a doorway protein.

Moved molecules against or with the concentration gradient

Bulk Transport

large molecules cant pass through membrane

Prokaryotic Cells

Cells that do not have a nucleus or organelles.

Unicellular

Bacteria or archaea

Eukaryotic Cells

Cells that have a nucleus, mitochondria and DNA

Unicellular or multicellular

Animals, plants, fungi

Size is limited by the ratio of cell surface to cell volume

Activation Energy

energy barrier that breaks existing bonds before creating new bonds. Rate of reaction depends on activation energy (higher = slower reaction)

Enzymes

Proteins that act as catalysts to lower the activation energy of a reaction.

Substrate

the molecule an enzyme interacts with

Active site

the location where an enzyme and substrate interact

Enzyme-Substrate Complex

The temporary complex formed when an enzyme binds to its substrate.

Cofactor

Non-protein helper molecules necessary for some enzymes to function.

o   Inorganic – inorganic cofactors (usually metal irons)

• Iron

• Magnese

• Zinc

o   Organic – coenzymes (commonly vitamins)

• Bond to the active site and help form the enzyme substrate complex

• Cosubstrates are detachable

• Prosthetic groups are permanent

Inhibitors

Molecules blocking or changing the shape of an enzyme's active site.

Denaturation

change in enzyme shape that makes it stop working

can be caused by high temperatures

Regulation

The control of enzyme activity by the cell.

o   Regulaor molecule controls shape of enzyme active site

• Causes enzyme to fit/not fit depending on what the cell needs

EX – oxygen for hemoglobin

Cellular Respiration

The process by which cells convert food into ATP.

Aerobic Respiration (steps)

(with Oxygen)

o   Glycolysis

o   Pyruvate Oxidation

o   Citric Acid Cycle

o   Electron Transport Chain

Glycolysis

(in the cytosol)

• glucose is split to make 2 molecules of pyruvate and 2 net ATP (pyruvate goes on)

• glucose+2ATP = 2 NADH + 4 ATP +2 PYRUVATE

Pyruvate Oxidation

(in the mitochondria)

• pyruvate converted into Acetyl CoA

• 2 PYRUVATE oxidize = 2 acetyl CoA + 2 NADH

Citric Acid Cycle (Krebs Cycle)

(in the mitochondria)

• Acetyl CoA is converted into different molecules (a little ATP and other molecules that are used in the electron transport chain)

• 2 Acetyl CoA = 6 NADH + 2 FADH2 + 2 ATP

Electron Transport Chain

• creates about 32 molecules ATP

• 1 NADH = 2.5 ATP

• 1 FASH = 1.5 ATP

Anaerobic Respiration

(without oxygen)

o   Produces very little ATP compared to aerobic

o   Lactic Acid Fermentation

• Lactic acid is a byproduct

o   Alcoholic Fermentation

• Ethanol is a byproduct

Photosynthesis

The process by which cells convert sunlight into glucose.

2 processes of Photosynthesis

o   Light reactions – harvest sunlight

o   Dark reactions

Light Reactions (photosynthesis)

• Take place in the thylakoid (inside chloroplast)

• Capture light and use it as an energy source

• Produce ATP and other molecules for dark reactions

• Produce O2 as a byproduct

Light Independent Reactions - Calvin Cycle (photosynthesis)

• Take place in the stroma (like the cytoplasm)

• Use ATP from light and CO2 from air to make molecules used in light reactions

• Produce glucose used in cellular respirations

Chromatin

DNA before replication

Chromosome

DNA wound up (only right before mitosis)

• wound around histones (proteins)

• a group of histones = nucleosomes

• Sister chromatids – copies of chromosomes made before mitosis

• Centromere – visible construction that holds the sisters together

Homologous chromosomes

have identical copies of the same gene in the same place. About the same size and shape and pair up before mitosis.

Ploidy (n)

o   denotes the number of copies of a gene/chromosome

Haploid – 1n

Diploid – 2n

Mitosis

The process of cell division that results in two identical daughter cells.

• Prophase – chromosomes condense (messy chromatin into tightly condensed chromosomes)

• Metaphase – chromosomes line up along the metaphase plate

• Anaphase – chromosomes are pulled at their poles

• Telophase – chromosomes de-condense back into chromatin

• Cytokinesis – parent cell splits into 2 identical daughter cells and both are 2n

Prophase

– chromosomes condense (messy chromatin into tightly condensed chromosomes)

Metaphase

– chromosomes line up along the metaphase plate

Anaphase

– chromosomes are pulled at their poles

Telophase

– chromosomes de-condense back into chromatin

Cytokinesis

– parent cell splits into 2 identical daughter cells and both are 2n

Meiosis

The process of cell division that results in four unique haploid cells.

• Same order and jobs as Mitosis, but there is one difference. Crossing over occurs during prophase I. This forms new combinations of genes that were not present in the parent cell.

Before Watson and Crick

o   1860s Fredrick Miescher – discovered phosphate rich chemicals in white blood cell nuclei. He was detecting phosphate groups in DNA

o   1920s Frederick Griffith – discovered that some kind of molecule transformed pneumonia bacteria from harmless to lethal

o   1940s Avery, MacLeod, McCarthy – DNA was what transformed from harmless to lethal

o   1950s Chase and Hersey – DNA, not proteins, were the genetic material

o   1950s Erwin Chargaff – A=T and C=G

o   1950s Roslind Franklin – X ray showed that DNA had helical structure

Watson-Crick Model of Nucleic Acids

Proposed by James Watson and Francis Crick in 1953, it describes the double helix structure of DNA and the base pairing rules (A-T and C-G).

DNA Replication

The process of copying DNA before cell division. It involves the unwinding of the double helix, reading of the template strand by DNA polymerase, and the synthesis of a new complementary strand. The end product is 2 identical helicies.

Mutations

Changes in the DNA sequence that can result from accidents during replication or exposure to carcinogens. They can be substitutions (wrong nucleotide used) or frameshifts (extra or missing nucleotide).

Control of Protein Synthesis

Genes are segments of DNA that serve as blueprints for specific proteins. Protein synthesis involves transcription (copying the gene from DNA to RNA) and translation (formation of proteins from the mRNA code).

Structural Genes

code for proteins that create organs, cell walls, and the cytoskeleton.

Regulatory Genes

• Regulatory genes code for proteins that regulate growth, control development, and start or stop transcription of certain genes.

Bacterial Genes

o   Prokaryotes – no nucleus

o   DNA can be changed more easily which is why we can become resistant to medicine

Transduction

A virus can put genes from one bacterium into another

Transformation

Bacteria can incorporate DNA from the environment into their own genes, allowing for the acquisition of new genes. This can lead to resistance to medicine.

Viruses

particles that have their own DNA or RNA and can only reproduce in host cells. They invade host cells, take control of DNA replication, and replicate themselves. They can reprogram the immune system and cause diseases.

Plant Organs

• Shoots are usually above ground and gather light and CO2 for photosynthesis.

• Leaves gather light

• Flowers attract pollinators and release pollen

• Fruits are mature reproductive organs containing seeds

• Roots absorb water and nutrients from the soil.

Water and Mineral Acquisition

Non-vascular plants lack transport tissues, while vascular plants have xylem and phloem for water, sugar, and mineral transport. Water and minerals diffuse into root cells and are pulled up through the plant via cohesion-tension.

Food Translocation and Storage

Sugar builds up in the phloem, and water helps move the sugar throughout the plant, forming sap. Some plants store carbohydrates as starch in stems or roots for later use.

Phloem

responsible for transporting sugars from leaves to the rest of the plant

Alternation of Generations

Plants have a life cycle that alternates between haploid and diploid phases. The sporophyte (diploid) produces spores via meiosis, which grow into gametophytes (haploid) via mitosis. Gametophytes produce gametes, which fuse to form new diploid individuals.

Gamete Formation and Fertilization

Plants have male (sperm) and female (egg) gametes. Sperm is produced in large numbers and can swim or be transmitted as pollen grains. Eggs are produced in small numbers and remain where they are. Fertilization occurs when the sperm and egg fuse.

Auxins (plant hormone)

o   Promote shoot elongation

o   Produced in the shoot tips

o   Transported from tip to base of shoot