Genetics Exam 1 Preparation 🧬

BIOL356 Dr. Sommars

central dogma of genetics

DNA→RNA→ Protein

chromosome theory of inheritance

inherited traits controlled by genes

diploid

The number of complete sets of chromosomes present in a cell or organism.

haploid

Cell with half the usual number of chromosomes. Occurs in sexual reproduction, where gametes are haploid. Allows for fusion of gametes to restore diploid chromosome number in offspring.

progeria

rare, fatal genetic condition of aging (defects in nuclear laminate), impaired cell division, loss of nuclear support

mitosis

receive diploid set of chromosomes

meiosis

receive haploid set of chromosomes

ploidy

number of complete sets of chromosomes in cell

homologous chromosomes

diploid cells have pairs of chromosomes

chromatin

unfolded and uncoiled diffuse network of genetic material in nucleus

metacentric

centromere in middle of chromosome

submetacentric

centromere between middle and end of chromosome

acrocentric

centromere close to end of chromosome

telocentric

centromere at end of chromosome

p arm

shorter arm of chromosome

q arm

longer arm of chromosome

karyotype

a visual representation of an individual's chromosomes, arranged in pairs according to size and structure

locus

identical gene sites along homologous chromosomes that encode the same traits they influence (one from each parent)

allele

different alternative form of the same gene

karyokinesis

Process of cell division where the nucleus divides into two daughter nuclei, each containing a complete set of chromosomes.

cytokinesis

separates the cytoplasm and organelles into two daughter cells and involves the formation of a cleavage furrow in animal cells or a cell plate in plant cells

interphase

G1, S, G2, the interval between cell divisions

S phase

genetic material replicates

G1 and G2

intensive metabolic activity, cell growth, cell differentiation but no division

G0

cells remain viable and metabolically active but no proliferative

cohesin

multi-subunit protein complex that holds sister chromatids together

kinetochore

assembly of multilayered plates of proteins associated with centromere

separase

cleaves cohesion holding sister chromatids

shugoshin

protects separase from cleaving its cohesin at the kinetochore; eventually gets degraded at anaphase

disjunction

sister chromatids disjoin and pulled to opposite ends of the cell 1) shugoshin must be degraded 2) cohesin complex holding centromere region of each sister chromosome is cleaved by separase 3) sister chromatids of each chromosome are pulled toward opposite poles of the cell

molecular motor

proteins that use energy generated by hydrolysis of ATP to shorten spindle fibers, drawing chromosomes to opposite ends of cell

kinase

enzymes that add phosphates to other proteins; a “master molecule” in conjunction with cyclins

cyclins

proteins that bind to kinases (creating cyclin-dependent kinases) activating them during the cell cycle and phosphorylating other target proteins that regulate cell cycle

Mendel’s 3 Postulates

1) Unit factors in pairs 2) dominance/recessivenes 3) segregation

Mendel’s 4th postulate

independent assortment

Dominance/Recessiveness Exceptions

• incomplete dominance

• codominance

• multiple alleles

• lethal alleles

Gene→ Trait exceptions

• gene interaction

• epistasis (type of gene interaction)

loss of function mutation

null mutation entirely lost; function diminished

gain of function mutation

function enhanced; more gene product

neutral mutation

function of WT unchanged