unit test #4 - inheritance Flashcards
how does asexual reproduction occur
with one parent, mitosis or binary fission
how does sexual reproduction occur
with 2 parents, meiosis
frequency of mitosis occurrence vs. meiosis occurence
mitosis: many times throughout life cycle
meiosis: once throughout life cycle
offspring in mitosis vs. meiosis
mitosis: offspring identical to parent
meiosis: offspring unique from each other and parent
changes in gene combinations in mitosis
gene combos maintained, new variations through mutation
changes in gene combinations in meiosis
new gene combinations made every generation
genetic variation in mitosis vs. meiosis
mitosis: none
meiosis: genetic variation is generated
adaptation on offspring produced by mitosis
can adapt to environment as well as parent
adaptation of offspring produced by meiosis
may adapt to environment better than parent
what stage of mitosis is DNA replicated
synthesis
order of mitosis
G1, S, G2, PMAT, C
homologous chromosomes definition
chromosomes in pairs: one maternal one paternal
- Two chromosomes with the same set of genes, in the same sequence, sometimes
with different alleles
what do homologous chromosomes have in common
size, centromere location, order of genes
what do homologous chromosomes have in difference
alleles
in a sexually reproducing organism, zygote performs ____ to grow into adult
mitosis
in sexually reproducing organism, adult performs ____ to form gametes
meiosis
how is a correct number of chromosomes maintained in each generation
- number of chromosomes in gametes must be reduced (half of diploid)
meiosis results in cells that have half the number of chromosomes as its parent, this is called….
reduction division
what are the male and female gonads
testes and ovaries
gametogenesis meaning
the ability to form gametes, process in which gametes are formed
names of gametogenesis in male vs female
male: spermatogenesis
female: oogenesis
cytoplasm division in sperm production
equal
cytoplasm division in egg production
unequal
motility of sperm vs egg
sperm: motile
egg: not motile
size/shape of sperm vs egg
sperm: long, small volume
egg: large spherical
food reserve in sperm vs. egg
sperm: small, enough to feed self
egg: large, enough for mitosis to form embryo
number of sperm vs. egg produced at once
sperm: many, often large numbers
egg: few, sometimes only 1
product of meiosis I
diploid germ cells split into 2 haploid cells
product of meiosis II
sister chromatids in 2 daughter cells separate forming 4 new haploid cells
what occurs during interphase
- diploid cell
- DNA = chromatin
- G1: synthesis of cell components + growth
- S phase: DNA replication–> 2 identical strands w centromere held tgt until anaphase II
- G2: cell prepares for meiosis
what occurs during prophase I
- nuclear membrane breaks down
- spindle fibres form
- DNA condenses into chromosomes
- synapsis
- crossing over
what occurs during synapsis
where homologous chromosomes pair up into tetrads
- genes of chromatids of homologous chromosomes align and attach with each other
what occurs during crossing over
sections of chromosomes(chiasma) cut + exchanged b/w homologous chromosomes
- new combos of alleles created–> combos different from parent
what occurs during metaphase I
- homologous chromosomes align at cell equator
- independent assortment: orientation of each homologous pair is random
what occurs during anaphase I
- homologous chromosomes separate and each chromosome moves towards opposite side of cell
- kinetochores attach chromosomes to spindle fibre
*sister chromatids NOT separated
what occurs during telophase I and cytokinesis
- occurs simultaneously
- new nuclei forms around chromosomes
- DNA uncoils: chromosomes–>chromatin
- spindle fibres break apart
- left with 2 unique haploid cells
what occurs during prophase II
- cells are haploid
- DNA condenses
- nuclear membrane breaks apart
- spindle fibres form
what occurs during metaphase II
- chromosomes align at equator in single file
what occurs during anaphase II
- sister chromatids pull apart from each other and move to opposite pole of the cell
- moved by microtubules
what occurs during telophase II and cytokinesis
- occurs simultaneously
- spindle fibres break apart
- DNA uncoils: chromosomes–> chromatin
- END with 4 unique haploid gamete
cells
chromosome numbers of parent+daughter cells in mitosis
- daughter cell = parent cell, same number of chromosomes
- maintains genome
chromosome numbers of parent+daughter cells in meiosis
- daughter cells = half number chromosomes of as parent
- reduces genome
uses of mitosis
grow/maintain/fix cells and tissues
uses of meiosis
creates gametes for sexual reproduction
what is variation within a species called
intraspecies variation
what are the 4 ways in which intraspecies variation can develop
- mutation (change in DNA sequence)
- gene flow (movement of genes b/w organisms (migration))
- meiosis (new gene combos)
- sexual reproduction (random fertilization b/w egg and sperm)
what are the 2 ways meiosis increases genetic diveristy
crossing over, independent assortment
chiasma meaning
location in which fragments of chromosome switch
recombinant chromosomes meaning
new combos of alleles created through meiosis (recombination)
bivalent meaning
pair of homologous chromosomes (tetrad)
how does independent assortment work
- each bivalent (tetrad) aligns independently so daughter cells get diff mix of chromosomes
- significant source of variation because 2^n possible different orientations in metaphase I and II combined
nondisjunction meaning
failure of chromosomes to separate correctly during anaphase I or II
what does nondisjunction result in
gamete cells with incorrect number of chromosomes–>zygote w/ incorrect # of chromosomes
- majority will be non-functioning egg/sperm
- most zygote/early embryo w/ incorrect # will not survive
what happens if nondisjunction occurs in anaphase I
- one gamete receives 2 copies of chromosome while other gamete receives none
- all resulting gametes after meiosis will have incorrect # of chromosomes
what happens if nondisjunction occurs in anaphase II
- half of the final 4 gametes will have an incorrect # of chromosomes
- other half will be unaffected
most common condition from nondisjunction
down syndrome
- has extra chromosome #21 (trisomy 21)
- not lethal however there are medical complications
why does nondisjunction in offspring increase with maternal age
- older women have less proteins that help keep chromosomes tgt leading to instability of homologous chromosome pairs
trisomy meaning
organisms with one extra chromosome
monosomy meaning
organisms with one less chromosome
genetic conditions caused by nondisjunction
- down syndrome (trisomy 21)
- patau syndrome (trisomy 13)
- klinefelter’s syndrome XXY (trisomy)
- turner’s syndrom XO(monosomy X)
inheritance definition
- a trait passed down from parent to offspring during reproduction
- refers to pathway of heredity
- DNA is molecule of inheritance
heredity meaning
transmission/the passing down of traits from one generation to another
where are male gametes of flowers found
in pollen grains on flower anther (found in stamen)
where are female gametes of flowers found
in ovules of flower ovary (found in carpel)
cross-pollination definition
when one plant fertilizes another plant of the same species
how can a gardener artificially cross-pollinate
- using paintbrush, brush stamen of one flower
- brush carpel of other flower
- enclose flower in sealed container preventing other pollen from entering
how did mendel discover the dominant and recessive traits
- established 2 true-breed populations with 7 different traits
- cross bred these population of each trait (ex. tall flower w/ short flower)
- resultant plants were always identical to one parent
- mendel allowed resultant plants to self-fertilize and found recessive trait had 1/4 chance appearance
what 2 things did mendel conclude/identify
- physical traits are determined by combos of what he had called “discrete heritable units” (now alleles)
- identified independent assortment
summary of alleles
- diff versions of same gene
- code for same type of protein
- differ by a base/sequence/large section
- new alleles can be generated by mutations which can form SNPs
- alleles are dominant/recessive to each other
genotype meaning
combinations of alleles for 2 copies of genes within diploid cells (genetic makeup of organsim)
homozygous meaning
having 2 of the same alleles of a particular gene
homozygous dominant: 2 dominant alleles
homozygous recessive: 2 recessive alleles
heterozygous meaning
having 2 different alleles of a particular gene
phenotype meaning
observable/physical traits or characteristics of an individual
what influences phenotype
both genes and environment
what traits are only affected by genotype
ABO blood group, PKU disease, hemophilia
what traits are only affected by environment
piercings, tattoos, scars
what traits are affected by both environment and genotype
height, type II diabetes, tanning
phenotypic plasticity meaning
refers to the fact that some genes can be turned on/off according to environment
phenotypic plasticity in tanning
- increase in sunlight: gene expression changes to increase synthesis of melanin
- decrease in sunlight: gene turned off to decrease synthesis of melanin
what is a punnet square representative of
- mendelian inheritance
autosomal meaning
gene located in autosome so males/females are equally affected
autosomal dominant disease example
huntington’s disease
autosomal recessive disease examples
cystic fibrosis, phenylketonuria (PKU)
what are carriers
individuals who carry a gene but don’t express it in their phenotype
how is phenylketonuria caused
mutation of PAH gene located on chromosome 12
normal allele in PKU
codes for functioning phenylalanine hydroxylase, an enzyme that converts AA phenylalanine to another AA called tyrosine
diseased allele in PKU
codes for non-functioning phenylalanine hydoxylase so phenylalanine from diet is not processed efficiently
what occurs in phenylketonuria
- phenylalanine accumulates, tyrosine is deficient
- nerve cells in developing brain are very sensitive to phenylalanine levels so excessive amounts lead to brain damage
current treatment for phenylketonuria
- prevent foods with high phenylalanine content from entering diet from birth
- PKU no longer causes intellectual and developmental disabilities in infants
incomplete dominance definition + heterozygous phenotype
one allele doesn’t have complete dominance over other, traits blend
codominance definition and heterozygous phenotype
two alleles that are equally dominant, simultaneous indepedant expression of both alleles
what is the normal and mutated allele for sickle cell anemia
normal: Hb^A
mutated: Hb^B
what is the inheritance pattern of sickle cell anemia
codominance
possible genotypes and phenotypes of sickle cell anemia
Hb^A Hb^A –> normal RBCs
Hb^A Hb^B –> sickle cell trait (some sickle cells some normal RBCs)
Hb^A Hb^B –> sickle cell anemia (all sickle cells)
limit to number of alleles of gene in population
no limit
what gene have greatest number of alleles why?
- immune response genes
- 32000 known alleles in major histocompatibility complex
- codes for glycoproteins that differentiate b/w self and non-self <– very important
what is the major histocompatibility complex (MHC)
group of genes on chromosome 6 that encode proteins that play key role in immune system
gene pool meaning
all genes and various alleles within a population
how many alleles can each person have
2, one from father one from mother
how do genes with multiple alleles affect apple trees
- each apple cultivar has unique combination of 2 alleles
- prevents self pollination as 2 diff alleles are needed for pollination
what do ABO genes code for
an enzyme that alters structure of glycoproteins on RBC membranes (antigens)
what does allele I^A do
adds acetylgalactosamine to glycoprotein (A type blood)
what does allele I^B do
adds galactose to glycoprotein (B type blood)
what does allele i do
adds nothing to glycoprotein (O type blood)
what antibodies will type A, type B, type AB and type O blood have
A: anti-B
B: anti-A
AB: none
O: anti-A and anti-B
antigen meaning
proteins found on RBC membranes
antibodies meaning
proteins in blood plasma that attach to corresponding antigens
what is the rhesus factor
- a protein on RBC that creates positive and negative blood types
- controlled by D+ or D- alleles
- pos: have rh antigens
- neg: do not have rh antigens
what is agglutination
the process that occurs if an antigen is mixed with corresponding antibody
how does agglutination in the blood occur
when the antibodies in the blood correspond with antigens from foreign blood causing them to attach and the blood to clump together
autosomes+ sex chromosomes in humans
autosomes: true homologous pairs (22 in humans)
sex chromosome: 23rd pair that determines sex
what determines male sex determination
Y chromosome - without it, will always be phenotypically female
what is the key gene on Y chromosome and what does it code for?
SRY gene –> codes for testis determining factor (TDF)
what happens without a Y chromosome
gonads develop into ovaries by default which secrete oestradiol <– hormone causing development of female reproductive system
what is klinefelter’s syndrome
- XXY sex chromosomes
- mostly male development with some female typical development
intersex definition
someone born with reproductive/sexual anatomy that doesn’t fit typical definitions of male/female
what are mosaic genetics
where have sex cells are XO and others are XY
why are most sex linked genes found on X chromosome
-larger in size, more genes than Y so there’s a higher chance of mutation
why do men have a higher chance of getting X chromosome based diseases
- only have 1 X chromosome, so whatever allele that carries will be allele expressed while females have 2 X chromosomes
normal vs. mutated hemophilia alleles
normal: provides instructions for making proteins for clotting process
mutated: code for altered/missing proteins that cannot effectively participate in blood clotting
why can’t men be carriers of sex-linked genes
only have 1 X chromosome so it will be expressed, while females can be carriers with one altered copy of gene
coagulation meaning
process where blood changes into solid state for clotting when blood vessels are damaged
who can type A blood donate to + receive
donate: A, AB
receive: A, O
who can type B blood donate to + receive
donate: B, AB
receive: B, O
who can type AB blood donate to + receive
donate: AB
receive: AB, A, B, O
who can type O blood donate to + receive
donate: A, B, AB, O
receive: O
who can type Rh+ blood donate to + receive
donate: Rh+
receive: Rh+, Rh-
who can type Rh- blood donate to + receive
donate: Rh+, Rh-
receive: Rh-
who is the universal donor, why?
O-, no antigens
who is the universal recipient, why?
AB+, no antibodies
pedigree chart meaning
- a diagram showing occurrence/appearance of phenotypes of particular gene through generations
what to look for to determine an autosomal dominant pattern in pedigree chart
- equally affected males + females
- affected ppl in every generation
- male to male transmission
- EVERY affected child has affected parent
- two affected parents have unaffected child
what to look for to determine an autosomal recessive pattern in pedigree chart
- equally affected males + females
- skipped generations
- appears in child but not in either parent
- if both parents affected, all children will be affected
what to look for to determine an x-linked dominant pattern in pedigree chart
- all daughters of affected male will be affected
- no male to male transmission
- if homozygous dominant female, all children will be affected
what to look for to determine an x-linked recessive pattern in pedigree chart
- more common in males than females
- all daughters of affected males are affected or carriers
- no male to male transmission if mother is unaffected and not carrier
- if affected mother + unaffected father, all sons will be affected
polygenic meaning + examples
phenotype affected by two or more genes (ex. height, skin colour)
effect of genes and environment on discrete phenotypes
influenced by one or few genes
not influenced significantly by environment
examples of discrete phenotypes
blood type, pea plant size
effect of genes and environment on continuous phenotypes
influenced by many different genes and influenced by environment
examples of continuous phenotypes
human height, skin colour
how is skin colour affected by alleles?
dominant alleles(ABC) = increased melanin production
recessive alleles(abc) = reduced melanin production
- 169 gene affect human colouration
- incomplete dominance
how does melanin in skin colour work, what is it affected by?
- melanocytes turn tyrosine–> melanin through complex process
- more melanin produced when exposed UV light and decreases without UV light
- affected by both UV exposure and genes
negative effects of UV and how genes have adapted to it
- mutations in DNA (cancer) <– may not be why genes adapted as they adapt to better produce offspring, however in many cases cancer doesn’t affect reproduction
- UV degrades folic acid –> nutrient needed for development of fetuses
positive effect of UV
- needed for synthesis of vitamin D required for absorption of calcium into bones
summary of histograms
- represents distribution of quantitative data in single set
- x: measurement
- y: frequency
summary of line/curve plot
- compare quantitative data to quantitative data
- x: quantitatively different groups
- y: mean value of each data set
summary of bar charts
- compares qualitative data to quantitative data
- x: qualitative groups
- y: mean quantitative data for each qual data set
summary of box and whisker plots
- compare quantitative data in diff data sets
- x: data sets to be compared
- y: median value for each data set
what does chi-squared test do
- compare collected data with theoretically expected data
what data is chi-squared test best used for
- discrete and categorical data
what stage of meiosis does reduction division occur
first division of meiosis
- diploid –> haploid
