AP Biology Review

Topics include: Ecol, Plants, Cells, Hormones, Biomes Genetics

mitosis

part of eukaryotic cell division during which the cell nucleus divides

cytokinesis

division of the cytoplasm during cell division

chromatids

one of the two identical "sister" parts of a duplicated chromosome

centromeres

area where the chromatids of a chromosome are attached

interphase

period of the cell cycle between cell division

cell cycle

series of events that cells go through as they grow and divide

prophase

first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the cell's DNA

centrioles

one of the two tiny structures located in the cytoplasm of animal cels near the nuclear envelope

spindle

fanlike microtubule structure that helps separate the chromosomes during mitosis

metaphase

second phase of mitosis, during which the chromosomes line up across the center of the cell

anaphase

the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles

telophase

fourth and final phase of mitosis, during which the chromosomes begin to disperse into a tangle of dense material

cyclin

one of a family of closely related proteins that regulate the cell cycle in eukaryotic cells

cancer

disorder in which some of the body's own cells lose the ability to control growth

genetics

scientific study of heredity

fertilization

process in sexual reproduction in which male and female reproductive cells join to form a new cell

true-breeding

term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate

trait

specific characteristic that varies from one individual to another

hybrids

offspring of crosses between parents with different traits

genes

sequence of DNA that codes for a protein and thus determines a trait

alleles

one of a number of different forms of a gene

segregation

separation of alleles during gamete formation

gametes

specialized cell involved in sexual reproduction

probability

likelihood that a particular event will occur

punnett square

diagram showing the gene combinations that might result from a genetic cross

homozygous

term used to refer to an organism that has two identical alleles for a particular trait

heterozygous

term used to refer to an organism that has two different alleles for the same trait

phenotype

physical characteristics of an organism

genotype

genetic makeup of an organism

independent assortment

independent segregation of genes during the formation of gametes

incomplete dominance

situation in which one allele is not completely dominant over another

codominance

situation in which both alleles of a gene contribute to the phenotype of the organism

multiple alleles

three or more alleles of the same gene

polygenic traits

trait controlled by two or more genes

homologous

term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent

diploid

term used to refer to a cell that contains both sets of homologous chromosomes

haploid

term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes

meiosis

process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

tetrad

structure containing 4 chromatids that forms during meiosis

crossing-over

process in which homologous chromosomes exchange portions of their chromatids during meiosis

Cell

Basic functional unit of all living things

Cytoplasm

Consists of specialized bodies (organelles) suspended in a fluid matrix (cytosol)

Plasma Membrane

Separates internal metabolic events from the external environment; controls the movement of materials into and out of the cell (selective permeability); lipid bilayer with hydrophilic heads and hydrophobic tails, proteins, cholesterol to provide some rigidity, and a glycocalyx of glycolipids (lipids + oligosaccharides) and glycoproteins (proteins + oligosaccharides)

Peripheral Proteins

Proteins that attach to the inner or outer surface of the membrane

Integral Proteins

Proteins that extend into the membrane

Transmembrane Proteins

Integral proteins that span completely through the membrane; held in place by hydrophilic/hydrophobic regions

Fluid Mosaic Model

Describes structure of the plasma membrane; scattered proteins within a flexible matrix of phospholipids

Channel Proteins

Provide open passageways through the membrane

Ion Channels

Allow the passage of ions across the membranes; gated channels open and close in response to specific stimuli i.e. Na+ and K+

Porins

Allow the passage of certain ions and small polar molecules; aquaporins increase the passage rate of water molecules

Carrier Proteins

Bind to specific molecules, undergo a change in shape, and then transfer the molecules across the membrane; i.e. the passage of glucose

Transport Proteins

Use ATP to transport materials through active transport; i.e. sodium-potassium pump maintaining higher sodium and potassium concentrations on opposite sides of the membrane

Recognition Proteins

Give each cell type a unique identification so it can distinguish between "self" and "foreign" cells

Adhesion Proteins

Attach cells to neighboring cells and give cell stability

Receptor Proteins

Provide sites that hormones or other trigger molecules can bind to in order to activate a cell response

Nucleus

Bounded by the nuclear envelope (consisting of two phospholipid bilayers); contains DNA in chromatin form; serves as the site of chromosome separation during cell division

Chromatin

Threadlike form of DNA

Chromosomes

Chromatin condenses during cell division into rod-shaped bodies

Nucleosomes

Before cell division, histones organize DNA into bundles

Nucleolus

Concentrations of DNA within the nucleus that are in the process of manufacturing components of ribosomes

Ribosomes

Consist of RNA molecules and proteins; the two subunits move across the nuclear envelope into the cytoplasm to be assembled; ribosomes assist in the assembly of amino acids into proteins

Rough Endoplasmic Reticulum

Stacks of flattened sacs with ribosomes; as ribosomes assemble polypeptides, polysaccharides are attached to them to create glycoproteins

Smooth Endoplasmic Reticulum

Without ribosomes; synthesizes lipids and hormones

Golgi Apparatus

Flattened sacs arranged like a stack of bowls; modify and package proteins and lipids into vesicles; these vesicles bud out from the Golgi apparatus, migrate to the surface, and merge with the plasma membrane to release contents

Lysosomes

Vesicles from the Golgi apparatus that contain digestive enzymes; break down food, debris, and foreign invaders; they DO NOT occur in plant cells

Peroxisomes

Break down substances (i.e. hydrogen peroxide, fatty acids, and amino acids)

Mitochondria

Carry out aerobic respiration to obtain ATP from carbohydrates

Chloroplasts

Carry out photosynthesis to convert energy from sunlight into carbohydrates

Microtubules

Made of tubulin; provide support and motility for cellular activities; found in spindle apparatus of mitosis, and in cilia and flagella

Intermediate Filaments

Provide support for the cell

Microfilaments

Made of actin; involved in motility of cell

Flagella and Cilia

Structures that protrude from the cell membrane and make wavelike movements; flagella are long, few and move in snakelike motion; cilia are short, numerous, and move with back-and-forth movement; "9 +2" array of microtubules

Centrioles and Basal Bodies

Act as microtubule organizing centers (MTOCs); a centrosome outside the nuclear envelope gives rise to microtubules making the spindle apparatus in cell division; basal bodies are at the base of cilia and flagella and are made of nine triplets of microtubules

Transport Vesicles

Move materials between organelles or between organelles and the plasma membrane

Food Vacuoles

Store nutrients temporarily; may merge with lysosomes which digest food with their enzymes

Storage Vacuoles

In plants; store starch, pigments, toxic substances (i.e. nicotine)

Central Vacuole

Large bodies in plant cells; exert turgor pressure on cell walls when full and maintain rigidity this way

Contractile Vacuole

Collect and pump excess water out of cell

Cell Wall

Provide support outside the plasma membrane; made of cellulose in plants; made of chitin in fungi

Anchoring Junctions

Protein attachments between adjacent animal cells; desmosomes bind adjacent cells together and are associated with protein filaments that extend into the cell interior to hold structures together

Tight Junctions

Tightly stitched seams between animal cells; prevents passage of materials between cells so that materials must pass through them

Communicating Junctions

Allow the transfer of materials; gap junctions between animal cells involve connexins which prevent cytoplasm from mixing but allow the passage of ions and small molecules; plasmodesmata between plant cells involves with a desmotubule surrounded by cytoplasm and plasma membrane going between the two cells, with exchange occurring through the cytoplasm

Solute

Substance being dissolved

Solvent

Substance that the solute is being dissolved in; i.e. water

Hypertonic Solution

The solution that has a higher concentration of solutes than the other solution

Hypotonic Solution

The solution that has the lower concentration of solutes than the other solution

Isotonic Solution

The solution has the same concentration of solutes as the other solution

Bulk Flow

Collective movement of substances in the same direction in response to a force or pressure

Passive Transport

Movement of substances from higher to lower concentration; does not require energy

Simple Diffusion

Random movement from high to low concentration

Osmosis

Diffusion of WATER molecules across a selectively permeable membrane

Dialysis

Diffusion of SOLUTES across a selectively permeable membrane

Plasmolysis

Movement of water out of a cell resulting in the cell's collapse

Facilitated Diffusion

Diffusion of solutes or water through channel proteins

Countercurrent Exchange

Diffusion of substances between two regions in which they are moving by bulk flow in oposite directions

Active Transport

Movement of solutes against a gradient, requiring the expenditure of energy

Exocytosis

Vesicles fuse with the plasma membrane and release their contents to the outside

Endocytosis

The plasma membrane engulfs a substance and enters the cytoplasm in a vesicle; phagocytosis (undissolved, solid material) and pinocytosis (dissolved, liquid material), receptor-mediated (specific molecules bind to receptors)

hypothalamic-releasing hormone

hormone produced in the hypothalamus that targets the anterior pituitary to release anterior pituitary hormones

hypothalamic-inhibiting hormone

hormone produced in the hypothalamus that targets the anterior pituitary to inhibit anterior pituitary hormones