Test 1 Study Guide

Question 1

Model organisms in genetics

Answer 1

short generation time, easy to maintain and grow in restricted space, easy to provide necessary nutrients for growth, well-understood development and growth, closely resemble other organisms or systems

Question 2

Watson & Crick

Answer 2

B-DNA, right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by ____ & ____ and the most common DNA structure in cells

Question 3

Mendel

Answer 3

“father of genetics”; pea plant experiments lead to the discovery of fundamental principles of inheritance (concepts of dominant and recessive traits), laws of segregation, independent assortment

Question 4

Gilbert & Sanger

Answer 4

discovered the exact sequence of the nucleotide building blocks in DNA

Question 5

Morgan & Sutton

Answer 5

Morgan: using fruit flies, he discovered a mutation affecting eye color allowing him to demonstrate how specific traits are linked to specific chromosomes

Sutton: chromosomes are the basis of heredity, reduction of chromosomes in meiosis is directly related to law of inheritance

= chromosome theory

Question 6

Allele frequency of a population

Answer 6

how common an allele is in a population;

Question 7

Sub-disciplines of genetics

Answer 7

molecular genetics, population genetics, transmission genetics (classical genetics), quantitative genetics, and developmental genetics

Question 8

Errors in chromosome separation/ nondisjunction

Answer 8

when chromosomes fail to separate properly during cell division, resulting in daughter cells with an abnormal number of chromosomes, often leading to genetic disorders like Down syndrome

Question 9

Significance of G2/M phase

Answer 9

checkpoint in the cell cycle near the end of G2; after this checkpoint has been passed, the cell undergoes mitosis; prevents cells from entering mitosis when DNA is damaged, providing an opportunity for repair and stopping the proliferation of damaged cells

Question 10

Significance of G1/S phase

Answer 10

checkpoint in the cell cycle near the end of G1; after this checkpoint has been passed, DNA replicates, and the cell is committed to dividing

Question 11

Significance of SRY in humans

Answer 11

sex-determining region Y; the male determining gene in mammals located on the Y chromosome

Question 12

Sex linked inheritance

Answer 12

the process by which genes on sex chromosomes are passed down from parents to their offspring. In humans, sex-linked traits are usually associated with the X chromosome, which has more genes than the Y chromosome
EX: colorblindness

Question 13

ZZ & ZW sex chromosomes

Answer 13

ZZ = males, ZW = females
in birds

Question 14

XX & XY sex chromosomes

Answer 14

XX = female, XY = male
in humans

Question 15

X and Y linked genetic disorders and inheritance pattern

Answer 15

X-linked genetic disorders are inherited through the X chromosome, meaning males are more likely to be affected due to only having one X chromosome, while Y-linked disorders are only passed from father to son as the Y chromosome is only present in males; both types of disorders exhibit distinct inheritance patterns based on the sex chromosomes involved

Question 16

Blood group inheritance pattern

Answer 16

codominance

Question 17

Transmission genetics

Answer 17

field of genetics that encompasses the basic principles of heredity and how traits are passed from one generation to the next

Question 18

Genome

Answer 18

complete set of genetic instruction for any organism

Question 19

Phenotype

Answer 19

appearance or manifestation of a characteristic

Question 20

Genotype

Answer 20

the set of alleles possessed by an individual organism

Question 21

Mutations

Answer 21

heritable change in genetic information

Question 22

Allele

Answer 22

one of two or more alternative forms of a gene

Question 23

Centromere

Answer 23

constricted region on a chromosome that stains less strongly than the rest of the chromosome; serves as the attachment point for spindle microtubules

Question 24

Double fertilization

Answer 24

fertilization in plants; includes the fusion of a sperm cell with an egg cell to form a zygote and the fusion of a second sperm cell with the polar nuclei to form an endosperm

Question 24

Telomere

Answer 24

stable end of a eukaryotic chromosome

Question 25

Barr body

Answer 25

inactivated X chromosome that appears as a condensed, darkly staining body in the nuclei of most cells of female placental mammals

Question 25

Test cross

Answer 25

a breeding experiment that determines the genotype of an organism by crossing it with a homozygous recessive organism

Question 26

Polydactyly

Answer 26

a condition where someone has more than 5 toes or fingers

Question 27

Variable expressivity

Answer 27

a genetic phenomenon where individuals with the same genetic condition have different signs and symptoms

Question 28

Lethal alleles

Answer 28

allele that causes death at an early stage in development; a recessive lethal allele kills individuals that are homozygous for the allele; a dominant lethal allele kills both heterozygotes and homozygotes

Question 29

Genomic imprinting

Answer 29

differential expression of a gene depending on whether it is inherited from the male or female parent

Question 30

Anticipation

Answer 30

phenomenon in which a genetic trait becomes more strongly expressed, or is expressed at an earlier age, as it is passed from generation to generation

Question 31

Hemizygous

Answer 31

possession of a single allele at a locus; males of organisms with XX-XY sex determination are hemizygous for X-linked loci because their cells possess a single X chromosome

Question 32

Consanguinity

Answer 32

mating between closely related people

Question 33

Monoecious

Answer 33

refers to an individual organism that has both male and female reproductive structures

Question 34

Dioecious

Answer 34

belonging to a species in which an individual organism has either male or female reproductive structures