AP Biology Unit Five

Genome

The genetic material of an organism or virus

Chromosomes

structures made of one DNA molecule and proteins

Somatic Cells

body cells

Gametes

reproductive cells

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes.

Centromere

Point on a chromosome by which it is attached to a spindle fiber during cell division.

Sister Chromatids

Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.

Mitosis

division of the nucleus into two identical daughter nuclei containing the same number of chromosomes

Cytokinesis

division of the cytoplasm to form two separate daughter cells(immediately after mitosis, meiosis I, or meiosis II.)

Meiosis

Cell division producing haploid gametes

Mitotic (M) Phase

mitosis and cytokinesis

Mitosis: Cell separates and divides chromosomes

Cytokines: Cell divides cytoplasm and organelles.

Interphase

Cell grows, replicates chromosomes, produces new organelles and cyclins.

G1 phase

Cell grows, duplicates organelles, and gathers materials for DNA replication.

S phase

DNA replication occurs

G2 Phase

growth and final preparation for division, nucleus well defined.

Mitotic Spindle

a structure made of microtubules that controls chromosome movement during mitosis

Centrosome

A structure that functions as the microtubule organizing center and is important during cell division, has two centrioles.

Kinetochore

A structure within the centromere containing the motor protein dynein. Moves the chromosomes apart during anaphase.

Cell Cycle Control System

A cyclically operating set of molecules in the eukaryotic cell that both triggers and coordinates key events in the cell cycle.

Cyclin

a protein that regulates the cell cycle

CDK

(Cyclin-dependent kinases) A protein kinase that is active only when attached to a particular cyclin. Activity rises and falls depending on the concentration of the cyclin partner.

MPF

(Maturation-promoting factor) a protein complex required for a cell to progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase.

growth factors

Regulatory proteins, ensure that cell division occurs properly

Density Dependent Inhibition

crowded cells stop dividing

Prophase

Chromosomes become visible, nuclear envelope dissolves, spindle forms

Metaphase

Chromosomes line up in the middle of the cell

Anaphase

the chromatids (Mitosis) or homologous chromosomes/chromatids (Meiosis) separate and move toward opposite poles

Telophase

The chromosomes begin to stretch out and lose their rodlike appearence. A new nuclear membrane forms around each region of chromosomes.

Cytokinesis in plants

cell plate forms

Cytokinesis in animals

Cleavage furrow forms

Binary Fission

one cell divides to form two identical cells

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

homologous chromosomes

Chromosomes that have the same sequence of genes, though may have different alleles (versions) of those genes. Maternal/Paternal

Sex Chromosomes

X and Y chromosomes.

Autosomes

non-sex chromosomes

Diploid

2 sets of chromosomes

Haploid

having a single set of unpaired chromosomes

Fertilization

Fusion of an egg and sperm cell

Zygote

diploid fertilized egg

Crossing Over

exchange of genetic material between homologous chromosomes during prophase I of meiosis

Tetrad

structure containing 4 chromatids that forms when homologs pair during meiosis

True Breeding

have identical alleles of a given gene/ homozygous

Hybridization

The cross of two true-breeding parents. (BB x bb)

P generation

Parental Generation

F1 generation

offspring of the P generation

F2 generation

offspring of the F1 generation

Alleles

Different forms of a gene

Punnet Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Homozygous

having two identical alleles for a trait. BB or bb

Heterozygous

having two different alleles for a trait. Bb

Phenotype

physical characteristics of an organism (blue eyes)

Genotype

genetic makeup of an organism (bb)

Mendel's Law of Segregation

Alleles segregate from one another during the formation of gametes. (due to independent assortment)

Monohybrid

A cross between individuals that involves one pair of contrasting traits

Dihybrid Cross

a cross between individuals that involves two pairs of contrasting traits

law of Independent Assortment

non-linked genes separate into gametes independent of one another in meiosis

Codominance

A condition in which both proteins produced by the alleles for a gene are fully expressed. (spots/stripes)

Incomplete Dominance

Cases in which one allele is not completely dominant over another. The two proteins produced by the alleles mix. (blended colors)

Multiple Alleles

A gene that has more than two alleles, like blood type (A,B,O)

polygenetic inheritance

many genes are involved in specifying traits that exhibit continuous variation (ie. a normal/bell-shaped curve). Ex: Human height, skin color

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Cystic Fibrosis

autosomal recessive disorder resulting in thick mucous in the respiratory tract.

Sickle Cell Disease

autosomal recessive disorder resulting in mutated hemoglobin molecules that polymerize and cause misshapen red blood cells.

Huntington's disease

autosomal dominant disorder resulting in neurodegeneration, leading to dementia and death.

Wild Type

An individual with the normal (most common in nature) phenotype. Ex: red eyes in fruit flies

Mutant

An individual with a mutated form of an allele, not common in nature. Ex: white eyes in fruit flies

Linked genes

Genes located adjacent on the same chromosome that tend to be inherited together in genetic crosses.

X inactivation

one of two X chromosomes in a female is randomly inactivated and remains coiled as a Barr body

Nondisjunction

Error in meiosis in which homologous chromosomes fail to separate.

Aneuploid

Abnormal number of chromosomes.

Monosomatic

Only has one copy of a chromosome

Polyploid

condition in which an organism has extra SETS of chromosomes

Deletion

removes a chromosomal segment

Duplication

repeats a segment

Inversion

reverses a segment

Translocation

moves a segment from one chromosome to another

Down Syndrome

(Trisomy 21) Occurs when an individual has 3 chromosomes of the 21st pair instead of 2; caused by NONDISJUNCTION

Turner Syndrome

A chromosomal disorder in females in which either an X chromosome is missing ( making the person XO instead of XX) or part of one X chromosome is deleted.

Extranuclear Genes

genes found in organelles in the cytoplasm; inherited maternally (mitochondria in the egg)

DNA methylation

The addition of methyl groups to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.

locus

Location of a gene on a chromosome