BIMS 320 - Exam 1

What is genetics?

the study of genes

Genetics is the science of _____.

heredity

What do geneticists study?

how traits and diseases are passed from one generation to another

How long have humans been aware of genetics?

10,000 years

What century was modern genetics developed in?

20th

Who began genetics as a practice?

Gregor Mendel

When did genetics as a practice begin?

1860s

phenotype

the observable traits of an organism

genotype

genetic constitution of an organism/ complete set of genes inherited by an individual

True or false: Genotypes change continually throughout development?

False

Genotypes change continually or are fixed?

fixed

True or false: Phenotypes change continually throughout development?

True

alleles

alternative forms of DNA within a single gene

Transmission genetics/ Mendelian genetics

the study of the transmission of traits in successive generations

Evolutionary genetics

the study of the origins of and genetic relationships among organisms and the evolution of genes and genomes

Molecular genetics

studies inheritance and variation of nucleic acids, proteins, and genomes

Chromosomal Theory of Inheritance (1902)

1) Chromosomes are the carriers of units of inheritance (genes)

2) Chromosomes maintain genetic continuity through generatios

the two scientists responsible for The Chromosomal Theory of Inheritance

Walter Sutton and Theodor Boveri

genes

the physical units of heredity; known to be defined DVM sequences

chromosomes

long molecules of double-stranded DNA and protein, which contain genes

homologous pairs/homologs

chromosomes that carry genes for the same traits (in sexually reproducing organisms)

Chromosomes of each species have unique:

number, size, morphology and banding

Where do genes reside?

chromosomes

True or false? Genes and chromosomes exist in pairs

true

Who identified DNA as the hereditary material?

Avery, MacLeod and McCarty

Deoxyribonucleic acid (DNA)

hereditary material in all organisms

Ribonucleic acid (RNA)

used by some viruses

DNA replication

precisely duplicates the DNA duplex prior to cell division

Messenger RNA (mRNA)

undergoes translation to produce proteins at structures called ribosomes

The 3 essential components to nucleotides:

1) nitrogenous base

2) pentose sugar

3) phosphate group

Nucleotides

building units of all nucleic acids

What does LUCA stand for?

last universal common ancestor

The 3 domains of life

1) eukarya

2) bacteria

3) archaea

template strand

the DNA strand from which the RNA is synthesized

coding strand

the complementary partner of the template strand

Criteria for model organisms of genetic study:

easy to grow, short life cycle, and produce many offspring

genomics

the study of whole genomes or genomes in their entirety

genome

the complete set of genetic information carried by a species

proteomics

focuses on the study of the complete set of proteins encoded in a genome

examines: protein function, localization, regulation and interaction

transcriptomics

studies the complete set of genes that undergo transcription in a cell

metabolomics

studies chemical processes involving metabolites in a specific cell, tissue, organ or organism

Mendelian inheritance

each parent contributes allele to their offspring

Non-mendelian inheritance

principles of Mendelian inheritance apply, but manifestation of the trait does not

5 features of Mendel’s breeding experiments that were critical to his success:

1) controlled crosses

2) used pure-breeding strains to begin experimental controlled crosses

3) selection of dichotomous traits

4) quantification of results

5) used replicate, reciprocal and test crosses

replicate crosses

repeating each cross several times, producing hundreds/thousands of progeny

reciprocal crosses

the same genotypes are crossed but the sexes of the parents are reversed

test crosses

crosses designed to determine the unknown genotype of an organism

locus

location of a gene on a chromosome (fixed position)

monohybrid crosses

cross that involve a single pair of contrasting traits

Law of segregation (Mendel’s 1st law)

describes the units of heredity, their separation into gametes and the random union of the gametes into progeny in predictable proportions

Law of independent assortment (Mendel’s 2nd law)

during gamete formation, the segregation of alleles at one gene is independent of a second gene

What is the forked-line diagram used to determine?

gamete genotypes and frequencies

product law

used to predict the frequency with which two independent events will occur simultaneously

The 4 rules of probability theory to describe and predict the outcome of genetic events:

1) product rule

2) sum rule

3) conditional probability

4) binomial probability

probability

the ratio of the number of times an event occurs out of the total number of events

product rule/ multiplication rule

the probability of two or more independent events is the product of each of their probabilities

sum rule/ addition rule

the probability of either of 2 mutually exclusive events occurring is the sum of their individual probabilities

conditional probability

involves questions asked after a cross has been made and is applied when information about the outcome modifies the probability calculation

binomial theorem

used to calculate the probability of any specific set of outcomes among a large number of potential events

chi-square test

used for quantifying how closely an experimental observation matches the expected outcome

pedigrees (family trees)

way of tracing the inheritance of traits in humans and some animals; shows a family tree with respect to a given trait

proband

the person who first came of attention to the geneticist when studying a pedigree

autosomal inheritance

refers to transmission of genes carried on autosomes (chromosomes found in both males and females)

haplosufficient gene

both +/+ and +/m produce sufficient amounts of protein product for a normal phenotype

haploinsufficient gene

one wild type dose produces insufficient amounts of protein products for a normal phenotype

wild-type alleles

prevalent alleles in a population

mutant alleles

alleles that have been altered by mutation (tend to be rare in natural populations)

Loss-of-function mutant allele

there is a significant decrease or complete loss of functional gene product

Gain-of-function mutant allele

the gene product acquires a new function or expresses increased wild-type activity

codominance

leads to heterozygotes with a different phenotype than that of either homozygote

two alleles at a locus produce different and detectable gene products in heterozygote (no dominance or recessiveness)

multiple alleles

when there are 3 or more alleles of the same gene in a population

lethal alleles

an allele that has the potential to cause the death of an organism

-typically the result of mutations in essential genes

gene-environment interaction

the influence of the environment on the expression of genes and on the phenotypes of organisms

pleiotrophy

the alteration of multiple distinct traits by a mutation in a single gene

gene interaction

the collaboration of multiple genes in the production of a single phenotypic characteristic or group of related characteristics

epistasis

gene interaction, resulting in altered phenotypic ratios

affects the normal 9:3:3:1 dihybrid ratios

duplicate gene action

encode the same product, or they encode products that have the same effect in a pathway or compensatory pathways

(genes in a redundant system)

recessive epistasis

homozygosity for the recessive allele at one locus will mask the phenotypic expression of the alleles at a second locus

dominant epistasis

the ability of a dominant allele at one locus to override or mask the interacting allele(s) of a second locus

complementary gene interaction

when genes work in tandem to produce a single product

complete penetrance

when a given genotype always produces the same phenotype

penetrance

the percentage of individuals that show at least some degree of expression of the mutant genotype in a population

expressivity

the range (degree) of expression of the mutant phenotype

variable expressivity

individuals who carry the alleles for a trait show a phenotype but to a varying degree of severity or form of expression

mitosis

leads to production of two cells, each with the same number of chromosomes as the parent cell

meiosis

converts the diploid number (2n) of chromosomes to the haploid number (n) and leads to production of gametes

sex chromosomes

determine sex and differ between sexes

TOPOisomerase II

unwinds DNA double helix

cohesion

keeps sister chromatids together

separase

cleaves cohesin and separates centromeres

securin

triggers anaphase, transports separase to the nucleus

Metaphase checkpoint requirements

pass if all chromosomes are attached to mitotic spindle

G1 checkpoint requirements

pass if cell size is adequate, nutrient availability is sufficient and growth factors are present

S-phase checkpoint requirements

pass if DNA replication is complete and has been screened to remove base-pair mismatch or error

G2 checkpoint requirements

pass if cell size is adequate and chromosome replication is successfully completed

karyotype

an image of a complete set of chromosomes photographed from a metaphase cell

karyokinesis

formation of 2 new nuclear membranes

cytokinesis

formation of 2 new cell membranes

meiosis 1

reductional division

meiosis 2

an equational division