genetics final exam review Flashcards
what is the hardy weinberg equation
p^2+2pq+q^2=1
2pq= frequency of heterozygous genotype
p^2 = frequency of homozygous dominant genotype
q= frequency of reccessisve allele
q^2 = frequency of homozygous reccesive
p^2 = frequency of homozygous genotype
what are the five assumptions of hardy weinberg equilibrum
random mating
no change in mutattion rate
no migration
no artificial selection
large population
what is the founder effect vs bottleneck drift
the founder effect occurs when population originates from smaller populations.
example: splitting of a small population to establish a colony
A genetic bottleneck occurs when a population is greatly reduced in size, limiting the genetic diversity of the species.
example original population composed of red and blue and a disaster happens causing a few red indivisuals to survuve and pass their genes to a new population.
disruptive selection
Selection for phenotypes at both extremes. Intermediates are selected against.
stabilzing selection
selects for intermediate phenotypes, with those at both extremes being selected against.
directional selection
phenotypes at one end of the spectrum become selected for or against, usually as a result of changes in the environment.
Ex: beak sizes in finches during dry years increased due to strong selection
in hardy weinberg equilibrum a population is evolving if
the allele frequencies change between generations
what is cystic fibrosis
thick mucus, lungs become clogged with mucus. the mucus eventually harbors bacteria and they have recurrent respiratory infections, is autosomal recessive
inability of chloride ions to cross epithelial cells (salivary, mucus and sweat glands, and pancreas)
what is a species
a species is a group of actually interbreeding organisms reproductively isolated
in nature from all such other groups.
what is speciation
speciation transforms parental species or divides single species into two or more seperate species.
what is genetic divergence and genetic drift
genetic divergence of populations can reflect action or natural selection, genetic drift or both
genetic drift is when a random event causes an increase or decrease in allele frequency
what is macroevolution
macroevolution is genetiic changes that result in reproductive isolation between two species
and leads to formation of species
what is the difference between prezygotic and postzygotic barriers
prezygotic barriers prevent mating from taking place due to behaivoral isolation and postzygotic barriers create reproductive isolation even when two members of two populations mate with each other because zygotes may be inviable and hybrids may be sterile .
what is phylogeny
genetic differences among PRESENT DAY SPECIES that can be used to construct their evolutionary history
define a phylogentic tree
a phylogentic tree is branvches that represent lineage over time and monophyletic groups consist of ancesteral groups and species.
what is sickle cell anemia
r genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape. Is autosomal recessive
what is hemophilia
an x linked blood linked clotting disorder
turnder syndrome is an example of what
turner syndrome is an example of a monosomy trait
transition mutation
an example of a transition mutation is when a purine replaces a purine
what is genetic drift
genetic drift are random fluctations in allele frequencies by change alone in small populations
what is natural selection
natural selection is a difference among indivisuals in survival or reproduction rate.
metacentric
when the centromere is located at the middle of the chromosome
penetrance
the percentage of indivisuals that sow at least some degree of expressio of a mutateed gene at the phenotype
nucleosome
is dna entwined around a octet of protiens
discondoradant
a pair of momozygotic twins where one is afflicted with osteoporosis and one is not
why is rna primer considered essentail during dna synthesis
the enzyme requires a free 3 oh group
in drosophila sex is determined by
the ratio of the number of x chromosomes to the number of autosomes
what are the post translational modifications
Translation generates a polypeptide chain. Modifications May be needed for a polypeptide chain to be functional to act as a protein.
1. Removal of N-terminus and C-terminus amino acid
2. Individual amino acids are sometimes modified
3. Glycoproteins
4. Cleave polypeptide chains
5. Signal sequences are removed
6. Polypeptide chains interact with metals
prb
inactivates the transcription factor e2f
frameshift
an insertion or deletion of a base that alters the reading frame
hunington diseases
a progressive neurodegenerative disorder causing lack of muscle. Is fatal. Is autosomal dominant. Is an example of a lethal allele. Although the individual will die, the effects are usually later in life.
marfan syndrome
A connective tissue disorder manifested by changes in the skeleton, eyes, and cardiovascular system. An autosomal dominant disorder
tay sach disease
A lipid storage disorder which is autosomal recessive.
-hexoaminidase is the enzyme involved in lipid metabolism and the enzyme is affected in this disorder.
-symptoms: neurodegenerative, psychosis, motor development, loss of voluntary motor skill
klinefelter syndrome
=males with an extra X chromosome, with 47 chromosomes in total. (47, XXY)
-phenotypes: incomplete sexual development (rudimentary testes and prostate), long limbs, large hands and feet, gynecomastia-breast tissue development
can see 48, XXXY or 48, XXYY or 49, XXXXY If nondisjunction happens more severely
jacobs syndrome
condition when a male has an extra Y chromosome. (47, XYY).
-results from father giving an extra Y in meiosis
-96% of males will be phenotypically normal
-modest phenotypes: increase in height, acne, and minor speech/ reading problems, personality disorders
triplo -x aneuploidy
a condition when a female has three copies of the X chromosome. (47, XXX)
-few modest effects on phenotype include tallness, menstrual irregularities and slight impact on intelligence.
neurofibromatosis
genetic disorder with multiple benign fibrous tumors that grow anywhere in the nervous system including the brain, spinal cord, and peripheral nerves. Is an autosomal dominant disorder.
reproductive isolating mechanisms
biological barriers that prevent or reduce interbreeding between populations.
Can be ecological, behavioral, seasonal, mechanical, or physiological.
griffith experiment
heat killed virulent bacteria and transformed the living nonvirulent bacteria.
avery maclead mcarthy
proved dna is the agent of transformation
hersey chase experiment
used radioactive phosphorous for dna and radioactive sulfur for protein to lable phage components and proved dna is the genetic matieral
telomerase
an enzyme that extends the end of a dna template and allows dna to be fully synthesized without shortening
what do dna polymerase 1 and 2 do
DNA polymerase I and II function in correcting mistakes made by DNA polymerase III . They detect and remove non complementary base pairs and have exonuclease activity in 3’ to 5’ direction.
rosalind franklin and watson crick
Used x-ray crystallography to study DNA structure. This technology aims to form a crystal of the molecule, mimicking its environment.
-this image shows the following features:
1. Right handed double helix
2. Chains antiparallel C-5’ to C-3’
3. Bases are 3.4 A apart
4. 10 bases per turn
5. Major and Minor grooves
6. Helix 20A in diameter
james watson and francis
developed the molecule model of DNA using information from many researchers
erwin chargaff
Discovered that DNA composition varies and created rules . There’s always equal amounts of purines to pyrimidines.
-Purines = pyrimidines
-(A+G) = (C+T)
- % of G+ C does NOT equal % of A+T
ligase
enzyme joins Okazaki fragments and seals other nicks in the sugar-phosphate backbone.
dna ploymerase 3
responsible for the 5’ to 3’ polymerization essential to in vivo replicatio
ozaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
dna ligase
Enzyme that joins two fragments of DNA to make a single fragment. It pastes together the Okazaki fragments together from the lagging strand.
leading strand vs lagging strand
The new complementary strand synthesized continuously along the template strand in the 5’ to 3’ direction is the leading strand.
the strand that is synthesized away from the replication fork , in pieces. Is discontinuous is the lagging strand.
dna topoisomerase
Enzyme that relieves overwinding strain ahead of replication forks on DNA during replication.
helicase
An enzyme that untwists the double helix of DNA at the replication forks.
middle repetitive dna
Consists of tandem repeats and interspersed retrotransposons
vntrs
variable number of tandem repeats. Are sequences 15-100bp in length which are repeated one after another in tandem. Are found within and between genes and often referred to as minisatellites
satellite dna
Variable DNA in short repeated sequences. Is a type of highly repetitive DNA.
Ex: CEN region, telomere
highly repetitve dna
DNA that consists of relatively short sequences that are repeated numerous times.
-satellite DNA is a type
messelson stahl experiment
proved that semi conservative replication is the nose used by bacterial cells to produce new DNA molecules.
-grew E.coli in different nitrogen dense mediums
sines
short interspersed elements that make up 13% of human genome. Example is the alu family which can
LINES
long interspersed elements that make up 21% of human genome. Are longer than 500 BP in length. Example is the L1 family in humans.
STRs
short tandem repeats. Are a group of tandemly repeated sequences smaller than 15bp in length. site. Also referred to as microsatellites.
interdispersed transpoons
short or long DNA sequences that can insert itself at a new location in the genome.
Types: SINES (less than 500 BP), LINES (longer than 500 BP)
describes the types of rna
messenger rna carries genetic information from DNA to the ribosomes
transfer rna Carries amino acids to the ribosome during translation
ribosomal rna type of RNA that makes up the major part of ribosomes, which helps to translate mRNA into protein
prader will syndrome
Occurs when a a deletion is inherited paternally.
-symptoms: short stature, mental retardation, low muscle
-prognosis: do well in monitored environments
angleman syndrome
Occurs when a deletion is inherited maternally.
-clinical features: feeding problems, delay in milestones, absent speech, severe learning disabilities, epilepsy, lack of pigmentation, laughter
-referred to as the happy puppet
-can never live on their own
variable expressivity
Says there is a range of expression of mutant genotypes.
Ex: FF or Ff forms of deafness. Different individuals with the same genotype may express it differently. Some may show mild, moderate, or profound forms of deafness.
incomplete penetrance
not all individuals with a disease-associated genotype will show the disease phenotype.
Ex: A person who had polydactyl may not be fully penetrant on that gene.
DD or Dd~ 80%~ polydactyl
DD or Dd~ 20%~ no polydact
x linked dominant versus x linked recessive trait
x linked dominant trait this type of trait is expressed in females with one copy
-males are often more severely affected because they don’t have another normal X to balance it out
his type of trait is always expressed in males
-affected males: inherited the trait from the mother are x linked reccesive triats
males versus females
females -have two X chromosomes (XX) that are each inherited from one parent.
-three possible genotypes: X⁺X⁺, X⁺Xᵐ, or XᵐXᵐ
males ve one X chromosome that was inherited from the mother are hemizygous only have one x chromosome
codominance versus incomplete partial dominance
both alleles are being expressed in a heterozygote
-2 distinct, detectable gene products exist
incomplete partial dominance when both alleles of a gene at a locus are partially expressed, often resulting in an intermediate phenotype. a blend
Ex: red and white parent flowers producing pink offspring in F1 generation
phenylketonuria
a disorder related to a defective recessive gene on chromosome 12 that prevents metabolism of phenylalanine (an amino acid)
ataxia Telangiectasia
an AR disease due to defect in DNA repair enzymes. Is an autosomal recessive disorder.
familal hypercholesteolemia
metabolic disorder that is caused by defective or absent receptors for LDLs on cell surfaces, that is inherited as an autosomal dominant trait.
what is the definition of transcription and translation
(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA
Translation (genetics) the organic process whereby the DNA sequence in a gene is copied into mRNa
meosis 1 vs meiosis 2
Meiosis 1: separation of homologous chromosomes
Meiosis 2: separation of sister chromatids
mitosis
Cell division where chromosomes are copied and distributed that each daughter cell receives a diploid set of chromosomes identical to the parent cell
meoisis
Cell division associated with gamete formation where the cells produced receive a haploid set of chromosomes
law of independant assortment
Two genes on different chromosomes segregate their alleles independently.
-the inheritance of one gene
independant product assortment law
When two independent events occur simultaneously, the combined probability of 2 outcomes is equal to the product of their individual probabilities.
ancondroplasdia
A form of dwarfism that is autosomal dominant. There’s a 50/50 chance of passing it on.
fragile x syndrome
most common form of inherited mental retardation. Is a result of the X chromosome having a fragile end (a segment more prone to breakage)
gene: FMR-1 shows gene anticipation and tri nucleotide repeat.
patau syndrome and edwards syndrome
Trisomy 13. “47, +13” patau
-Is lethal
-major abnormalities-microcephaly, open sutures, heart, kidney, neurological, cleft lip/palate, polydactyl, clenched fists
-increase in father’s age increases the risk
familal down syndrome
Caused by a Robertsonian translocation in which the long arm of chromosome 21 is translocated to another chromosome; tends to run in families.
-chromosome 14 and 21 create a translocation carrier
-will appear phenotypically normal but have 45 chromosomes
robertonsian translocation
When two nonhomologous acrocentric (having centromere close to the end) chromosomes break at the centromere and long arms fuse
pericentric inversion
inversion that includes the centromere in the inverted sequence
allyopolypoidy
polyploidy resulting from contribution of chromosomes two closely related species or different species
autopolyploidy
an individual that has more than two chromosome sets that are all derived from a single species.
Failure of segregation.
2. Cell never divides and goes directly to interphase.
3. Dispermy
4. Experimental conditions
autotriploid
A 3n polyploid that has one extra set of chromosomes, identical to the normal haploid complement of the same species. They produce unbalanced gametes and cannot propagate sexuall
autotetraploid
a 4n polyploid that has two extra sets of chromosomes, identical to the normal haploid complement of the same species. They produce balanced gametes and can propagate sexually.
