EXAM 3 Flashcards
mendels law of segregation: relation to chromosome movement
-each individual has 2 factors for each trait
-the factors separate during the formation of gametes
-each gamete contains only one factor from each pair of factors
-fertilization gives each new individual two factors for each trait
mendels law of independent assortment: related to chromosome movement
each pair of factors separates independently
-all possible combinations of factors can occur in the gametes
what is an allele? D vs R
an allele is an alternative form of a gene, they occur at the same locus on homologous chromosomes
-dominant allele will mask the expression of the recessive allele
-recessive will only exert its effect in a homozygote
genotype vs phenotype
genotype: alleles the chromosomes carry responsible for the trait (the letters)
phenotype: individual’s actual appearance (effect of letters)
patterns of inheritance: G and P OUTCOMES
homozygous: 2 of same allele
heterozygous: 2 different alleles (recessive allele is masked by dominant)
-homo dom= DOMINANT
-hetero= DOMINANT
-homo recess. = RECESSIVE
2 HETEROZYGOUS CROSSED IN MONOHYBRID =
genotype= 1:2:1, phenotype= 3:1
TEST CROSS = unknown genotype crossed with homo recess.
autosomal dominant vs autosomal recessive
RECESSIVE: most children who are affected have parents who are not affected
-heterozygotes (Aa) have an unaffected phenotype
-2 parents who are affected will always have children who are affected
-close relatives who reproduce are more likely to have children who are affected
DOMINANT: children who are affected will usually have a parent who is affected
-heterozygotes (Aa) are affected
-2 parents who are affected can produce a child who is NOT affected
-2 parents who are UNaffected will NOT have children we are affected
-both males and females are affected with equal frequency
Tay Sacchs
recessive disorder!!
-occurs among jewish people
-lack of enzyme Hex A and subsequent storage of its substrate in lysosomes
-development is slowed down in 4-8 months old causing neurological impairment, psychomotor difficulties, blind, seizures, and paralysis
cystic fibrosis
recessive disorder!!
-most lethal in white people lol
-chloride ions fail to pass thru plasma membrane (lack of water causes mucus in bronchial tubes which interferes with lungs and pancreas
-difficulty breathing and digesting
sickle cell disease
recessive disorder!!
-red blood cells are irregular caused by abnormal hemoglobin
-clog vessels causing poor circulation, anemia
-hemorrhaging leads to jaundice, pain in abdomen and joints, and damage to internal organs
-prevents malaria tho?
huntington disease
dominant disorder!!
-leads to degeneration of brain cells
-caused by mutated copy of huntingtin
-effects in teen years then by 10-15 years death will happen
incomplete dominant vs codominance
incomplete: heterozygous has intermediate phenotype between homozygotes (red flower + white flower = pink flower)
codominance: both alleles are expressed in heterozygous (red flower + white flower = red and white flower)
polygenic inheritance
trait controlled by 2 or more genes
-dominant alleles are additive
-results in continuous variations of phenotype (skin and height)
special characteristics of inheritance for ABO blood types
IA= A anitgen
IB= B antigen
i= neither A or B
-IA and IB are dominant over i
-IA and IB are codominant
BLOOD TYPES
A: IAIA OR IAi
B: IBIB or IBi
AB: IAIB
O: ii
environment vs genetic trait
nutrition and temperature can influence genetic trait
ex: height influenced by nutrition
-temp of egg incubation determines sex
-himalayan rabbit produces melanin only at low temp
why might scientists determine if a trait is strongly affected by environment
the argument nature vs nurture!!
-identical twins live in different environment and both contain same trait, then its genetics
-behavioral traits are partly heritable
on the other hand, if you have a genetic disorder, changing diet can minimize effect of the disease
linked genes
genes inherited together
DO NOT SHOW INDEPENDENT ASSORTMENT because linked alleles are all on one chromosome and are inherited together
-crossing over between non sister chromatids on homo chrom.
-22 autosomes and 1 pair of sex chrom
X linked inheritance
male receives X-linked allele from mother’s X chromosome
phenotype and genotype predictions based on sex linked traits
A Homozygous man X hetero (carrier) woman will give the sons a 50% chance of being affected and the daughters a 50% chance of being a carrier (but wont be affected)
x-linked recessive = more men than woman affected because recessive alleles on X chrom are always expressed in guys
x-linked dominant = affected males only pass down to daughters who have 100% chance of being affected
duchenne muscular distrophy
x-linked recessive!!
-wasting away of muscles, absence of protein
-waddling gait, toe walking, frequent falls, difficulty rising, muscle weakness,
-death by 20, males are rarely fathers
-proteins remains by passing from carrier mom to daughter
hemophilia
x-linked recessive!!
-affected persons blood does not clot, bleed internally around joints
-can be stopped by transfusions of blood/plasma
Hemo. A = absence of clotting factor VIII
Hemo. B = absence of clotting factor IX
how do chromosomes disorders arise
NONDISJUNCTION!!
failure of homo chrom. or sister chromatids to separate during either mitosis or meiosis, produces cells with abnormal chromosomes
trisomy: extra chromosome
monosomy: one less chromosome
down syndrome
autosomal trisomy!!
short stature, eye lid fold, flat face, stubby fingers, large fissured tongue, mental impairment
-happens by nondisjunction of an extra copy of chromosome 21
-chances of having a kid with zds increases at the age of 40
turner syndrome
-only 1 chromosome (X)
-short with webbed neck, high palate, small jaw
-congenital heart and kidney defects
-ovarian failure and do not undergo puberty
-NO mental impairment, can live healthy life
klinefelter syndrome
male has 2 or more x chromosomes in addition to the Y
-extra X is called Barr body
-testes and prostate gland are underdeveloped
-breasts, large hands and feet, slow to learn, increased chance of lupus and breast cancer
poly-x females
more than 2 x chromosomes in females
-tall and thin
-possibility of menstrual difficulties but most are fertile
-more than 3 x chromosomes = intellectual disabilities
chromosomal deletion
chromosome loses an end piece due to break
chromosomal duplication
chromosome segment occurs more than once
chromosomal translocation
movement of one chromosome segment from one chromosome to another
extra material from one, missing material fro another (abnormalities)
chromosomal inversion
segment of chromosome is turned 180 degrees (opposite)
List two observations Darwin made on his voyage that influenced the development of his theory
He visited tropical rainforests and other new habitats where he saw many plants and animals he had never seen before (see Figure below). This impressed him with the great diversity of life
-He dug up fossils of gigantic extinct mammals, such as the ground sloth (see Figure below). This was hard evidence that organisms looked very different in the past. It suggested that living things—like Earth’s surface—change over time.
Compare and contrast Darwin’s and Lamarck’s explanations as to how evolution might happen
Lamarck: acquired characteristics- environment can bring about inherited change
ex: giraffe with short necks stretch out their necks to eat leaves, so offspring have longer necks (NO EVIDENCE FOUND FOR THIS LOL)
Darwin: natural selection- traits with an advantage are passed down in fertile offspring
ex: giraffes with already taller necks survive while shorter necks die making taller gene last longer in giraffe population
Describe how theory on natural selections suggests how evolution might work
-individual organisms within a species exhibit variation that can be passed down from generation to the next (variation must be heritable)
-organisms compete for available resources
-individual organisms within a population differ in terms of reproductive success (more energy = more reproductivity)
-organisms become adapted to conditions as the environment changes
biological evolution
all the changes that have occurred due to reproductive success in living organisms over geological time
fossil evidence for evolution
FOSSIL (remains and traces of past life)
-hard body parts most often preserved (bone, teeth, pollen, wood, shells)
-majority embedded in sedimentary rock and deposited in layers called strata (younger on top, older on bottom)
mold: harded rock with air space
cast: silica fills that space
five conditions necessary for the allele frequencies in a population to be in Hardy-Weinberg equilibrium.
- no mutation
- no genetic drift
- no gene flow
- random mating
- no selection
Calculate the genotypic frequencies for a population
just do the math emma
five forms of microevolution
mutations: alteration in allele frequency in a population
-w/o it there would be no inheritable diversity, are random!!
genetic drift: chance events that change allele frequency from one generation to the next
-bottle neck effect: catastrophes like hurricanes and volcanoes that kill off a lot of individuals
-founder effect: few individuals colonize on an island or new habitat (birds going from forest to the beach)
gene flow: movement of alleles between a population
-Individuals or their gametes migrate from one population to another and breed in the new population
-gene flow increases diversity
nonrandom mating: individuals are selective about who their mate is
natural selection: fitness (ability of organism to reproduce fertile offspring)
each type of microevolution & Define heterozygote advantage and give an example
stabilizing selection: against extreme phenotype for average (tigers cant have long tails bc they will trip, tigers cant have short tails because they will lose balance, so medium works)
directional selection: extreme phenotype is favored!!! long tails for lizards make it look like a snake so they stay alive from predators
disruptive selection: both extreme phenotypes work but not average (long squirrel tail good for intimidation, short squirrel tail good from running, medium does not do anything
heterozygote advantage: only alleles that are expressed are subject to natural selection
example: recessive dies due to malaria, hetero isn’t affected by any, dominant dies due to sickle cell
various forms of species isolating mechanisms
habitat isolation: separated by location (snakes in water can’t mate with snakes on land)
temporal isolation: breeding at different times or seasons (skunk breeds in fall, another breeds in winter)
behavioral isolation: different courtship rituals (bluefoot boobies do a lil dancy dance while masked boobies practically makeout)
mechanical isolation: physical incompatibility (penis does not fit vag)
gametic isolation: molecular incompatibility of sperm and eggs
