Mendel Flashcards
1
Q
before mendel, what did people believe in for heredity?
A
blending hypothesis - how blue and yellow make green
2
Q
what did mendel introduce?
A
particulate hypothesis - discrete units called genes passed on from parents to offspring retain their separate identity
analogous to marbles in a bucket being passed into offspring
3
Q
what did gregor mendel do as a profession?
A
monk
4
Q
what did mendel work with?
A
pea plants
5
Q
nickname of mendel?
A
Father of Genetics
6
Q
what is an angiosperm?
A
flowering plants
7
Q
parts of an angiosperm? (8)
A
petal
sepal - encase flower
filament - holds the pollen sack
anther - pollen sack
ovary
style - neck of ovary
stigma - sticky part of flower
stem
8
Q
eggs of flowers
A
ovules
9
Q
male parts of angiosperm
A
stamen - filament and anther
10
Q
female parts of angiosperm
A
pistil/carpal - style and ovary
11
Q
what is the mating of 2 varieties called?
A
hybridization
12
Q
the mating of one character? two characters?
A
monohybrid; dihybrid
13
Q
what did mendel’s experiment prove incorrect?
A
the blending model of inheritance was inccorect
14
Q
what did the purple x white flowers in the p generation produce?
A
all purple flowers, not pale
therefore, purple flower color is dominant to white
15
Q
how many characters did mendel observe the pattern of inheritance?
A
6 other - 7 total
16
Q
what is the ratio of inheritance of mendel’s experiment?
A
3:1
17
Q
how did mendel explain the ratio inheritance? (4)
A
1) alternate versions of genes account for variation (alleles)
2) organism inherits 2 alleles (mom and dad), and thus a genetic locus is represented twice in diploid organism- either heterozygous or homozygous
3) if alleles differ, dominant allele is expressed in phenotype, while recessive is not seen
4) Law of Segregation
18
Q
Law of Segregation
A
the 2 alleles present in a cell segregate during meiosis, accounting for the haploid number in sperm and eggs
19
Q
identical alleles
A
homozygous
20
Q
alleles differ
A
heterozygous
21
Q
how an organism looks
A
phenotype
22
Q
genetic makeup
A
genotype
23
Q
can we tell the genotype of a purple flower?
A
no it can be PP or Pp
24
Q
what is test cross?
A
when you cross a mysterious organism with a homozygous recessive one to determine genotype
25
if all offspring have purple in a test cross what is the genotype?
PP
26
if half are purple and other half white after a test cross, what is the genotype?
Pp
27
how did Mendel discover his 2nd law?
performing dihybrid
he questioned whether 2 characters were inherited as a package or separately
28
what is mendel 2nd law?
Law of Independent Assortment
in a dihybrid, the two alleles for one character assort independently of the two alleles of another character
29
Law of Independent Assortment
traits separate and produce 4 gametes
30
4 gametes of RrYy
RY, Ry, rY, ry
31
genotype of RrYy x RrYy
1:2:1:2:4:2:1:2:1
32
phenotype of RrYy x RrYy
9:3:3:1
33
Law of Large Numbers
probability is closer to predicted results when sample size is increased
34
what does dominant really mean?
- not mean trait is more common (Polydactyly is dominant)
- it doesn't mean the allele subdues a recessive allele
- it just is a working gene that makes a normal/functional protein
35
how does roundness come about in a pea rather than wrinkles?
due to the Prescence of an enzyme that converts simple sugars to starch
round peas have starch, wrinkled don't
wrinkles store simple sugars rather than starch, so with osmosis water enters causing to to swell, and wrinkle when it dries
36
Incomplete Dominance
F1 hybrids have an appearance in between 2 parentals
red + white = pink
37
Why isn't Incomplete Dominance evidence for blending?
blending suggests all offspring would be the intermediates-not true
38
what did Mendel's pea plants exhibit?
Complete/Simple Dominance
39
Codominance
both alleles are expressed in phenotype
40
example of codominance with human blood groups
M, N, MN
M individual - MM
N individual - NN
MN individual - MN
41
Mutiple Alleles
exist in populations with more than 2 allelic forms
AB^O blood group has three different alleles of one gene
42
what do A, B, AB, O blood types represnet?
two sugars that are either present or absent on the surface of RBC's - A substance and B substance
43
A blood group
Phenotype: A
Genotype: I^AI^A or I^Ai
Antibodies present: Anti-B
Compatibility with other blood types: agglutination with B and AB, A and O compatible
44
B blood group
Phenotype: B
Genotype: I^Bi^B or I^Bi
Antibodies present: Anti-A
Compatibility with other blood types: agglutination with A and AB, compatible with B and O
45
AB blood group
Phenotype: AB
Genotype: I^AI^B
Antibodies present: none
Compatibility with other blood types: compatible with all
46
O blood group
Phenotype: O
Genotype: ii
Antibodies present: Anti-A and Anti-B
Compatibility with other blood types: compatible only with O
47
Example of codominance in blood type
AB are both expressed
48
Pleiotrophy
gene affects an organism's phenotype in many ways
ex. sickle cell anemia is caused by a single gene, causing RBC to change their shape, resulting in multiple symptoms
49
epistasis
when a gene at one locus affects the phenotypic expression of a gene at another locus
50
epistasis ex
Black fur dominant to brown
BB, Bb= black
but if CC, Cc (a gene that controls pigment) is present, color will show
if cc, mouse is albino regardless of genotype
51
Polygenic Inheritance
seen with human skin color and height - when a character varies along a continuum
52
what is polygenic inheritance define as?
the additive/quantitative effect of two or more genes on a single phenotypic character
53
polygenic inheritance example
with skin color, each dominant allele contributes to darker skin color and each recessive gene to lighter color
AABBCC - six units of darkness, so skin will be very tan
aabbcc - six units of lightness, skin will be very pale
AaBbCc and AABbcc - both have 3 units of darkness, so skin will be same tone
54
what is phenotype also determined by?
environment
nature (gene) and nurture (environment) both influence all traits
55
example of nature
genotype
56
example of nurture
nutrition, exercise, expose to sunlight
57
what is the nurture side of the debate the broadest for?
polygenic traits like skin color and height
58
example of how environment affects an organism is seen in flowers
hydrangea - same genetic varieties produce a range of colors from pink to white to purple based upon the soil pH
59
how to geneticist analyze mating of humans?
pedigrees
60
what can pedigrees be used for?
track a trait across generations to understand the past and to predict the future
61
when an allele causes a genetic disorder, what are the possible reasons?
either a malfunction of a protein or no protein at all
62
why do heterozygous individuals regarding recessive disorders express the "normal" phenotype?
one copy of the normal allele produces some of a specific protein
63
what are heterozygotes that are phenotypically normal called?
carriers
64
when does a recessively inherited disorder show up in?
homozygous recessive individuals
65
why are genetic disorders not evenly distributed among all groups of humans?
past conditions when the world was less industrialized, and people were more geographically isolated
66
most common recessive lethal genetic disease in white in the US
cystic fibrosis
67
what is cystic fibrosis
affects Cl- transport between cells and the interstitial fluid
the protein channels that transport chloride in and out of the cell are defective or absent in people with cystic fibrosis
causes Cl- to build up that leads to mucus build up around organs and air pathways as well as bacterial infection
68
Tays Sechs
recessive disorder where a dysfunctional enzyme fails to break down lipids in the brain - causes seizures, blindness, and degeneration of motor and mental perfomrance
69
sickle cell anemia is common in what descent? why?
African descent
1/10 African Americans are carriers of this allele
in certain environments in Africa, heterozygotes have an advantage over hom. dom as they have resistance to malaria
plasmodium only infect normal RBC
70
what is sickle cell anemia?
substitution of 1 amino acid in the hemoglobin protein RBC's causes to sickle
sickled cells hold less oxygen
71
what type of dominance is sickle cell anemia?
incomplete as individuals who are heterozygous suffer some of the symptoms due to a fraction of their RBC sickled
72
most harmful alleles are?
recessive
73
example of dominant disorder
Achondroplasia = form of dwarfism expressed in individuals with AA or Aa
99.99% of population is aa
AA = fetal death
74
many lethal dominant alleles results due to?
mutations
75
example of dominant disorder that does not show up until age 35-35
Huntington's disease - degeneration of the nervous system
76
amniocentesis
inserting needle into amniotic fluid surrounding the fetus around the 14th-16ht week of pregnancy
77
how is the fluid taken from amniocentesis tested?
1) tested with chemicals for certain disorder
2) the cells from the fluid are grown in a lab and within weeks a karyotype can identify chromosomal defects
78
CVS
chronic villus sampling
doctor suctions out fetal tissue from the placenta around the 8th to 10th week of pregnancy
fetal tissue is then karyotyped immediately, giving results within 24 hours
79
what type of means are CVS and aminocentesis to check for abnormalities?
invasive means
80
noninvasive way to check for abnormalities?
ultrasound - uses sound waves to prdce image of fetus
81
risk of invasive procedures
som risk of maternal bleeding or fetal death, and therefore are reserved for only extreme risk cases
82
how big was Mendel's sample?
many varieties
83
how were the pea plants easy to control?
remove make stamens of parentals so they could not self-fertilize
84
how were the traits of the pea plants?
either - or
85
how did mendel start his experiment?
true breeding/purebred varieties
all parentals were homozygous
86
how long did mendel follow his experiment?
at least 3 generations
P (parental), F1(first filial) that self-pollinate, F2
87
what type of analysis did mendel use?
quantitative analysus
88
what did the large number of offspring/sample provide?
high probablilty
89
how were the peas easy maintain?
short life cycles
