Test 1 Study Guide Flashcards
Model organisms in genetics
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
Watson & Crick
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
Mendel
“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
Gilbert & Sanger
discovered the exact sequence of the nucleotide building blocks in DNA
Morgan & Sutton
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
Allele frequency of a population
how common an allele is in a population;
Sub-disciplines of genetics
molecular genetics, population genetics, transmission genetics (classical genetics), quantitative genetics, and developmental genetics
Errors in chromosome separation/ nondisjunction
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
Significance of G2/M phase
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
Significance of G1/S phase
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
Significance of SRY in humans
sex-determining region Y; the male determining gene in mammals located on the Y chromosome
Sex linked inheritance
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
ZZ & ZW sex chromosomes
ZZ = males, ZW = females
in birds
XX & XY sex chromosomes
XX = female, XY = male
in humans
X and Y linked genetic disorders and inheritance pattern
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
Blood group inheritance pattern
codominance
Transmission genetics
field of genetics that encompasses the basic principles of heredity and how traits are passed from one generation to the next
Genome
complete set of genetic instruction for any organism
Phenotype
appearance or manifestation of a characteristic
Genotype
the set of alleles possessed by an individual organism
Mutations
heritable change in genetic information
Allele
one of two or more alternative forms of a gene
Centromere
constricted region on a chromosome that stains less strongly than the rest of the chromosome; serves as the attachment point for spindle microtubules
Double fertilization
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
Telomere
stable end of a eukaryotic chromosome
Barr body
inactivated X chromosome that appears as a condensed, darkly staining body in the nuclei of most cells of female placental mammals
Test cross
a breeding experiment that determines the genotype of an organism by crossing it with a homozygous recessive organism
Polydactyly
a condition where someone has more than 5 toes or fingers
Variable expressivity
a genetic phenomenon where individuals with the same genetic condition have different signs and symptoms
Lethal alleles
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
Genomic imprinting
differential expression of a gene depending on whether it is inherited from the male or female parent
Anticipation
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
Hemizygous
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
Consanguinity
mating between closely related people
Monoecious
refers to an individual organism that has both male and female reproductive structures
Dioecious
belonging to a species in which an individual organism has either male or female reproductive structures
