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HL Bio > 3.4 inheritance > Flashcards

3.4 inheritance Flashcards

1
Q

what did GREGOR JOHANN MENDEL discover

A

the basic underlying principles of heredity (thru work on garden pea plants)

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2
Q

define Mendel’s Laws

A

3 fundamental laws of inheritance
that apply to sexually reproducing species

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3
Q

state the 3 mendels laws

A

law of segregation

law of independent assortment

law of dominance

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4
Q

what is the law of segregation

A

each gamete has only 1 allele for each gene!!! –>
2 alleles (on 2 chromosomes) seperated during meiosis (anaphase 1)
- HENCE alleles are passed generation to the next as distinct units

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5
Q

exceptions to law of segregation

A

alleles in sex chromosomes and mitochondrial DNA

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6
Q

what is the law of independent assortment

A

allele inherited for one trait DOES NOT AFFECT the allele inherited for another trait
+
gamete has one copy of each gene – result of random orientation of homologous chromosomes (metaphase I)

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7
Q

exception to law of independent assortment

A

linked genes

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8
Q

what is the law of dominance

A

when 2 diff alleles:
dominant determines trait, recessive in unexpressed

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9
Q

exception to law of dominance

A

co-dominance

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10
Q

diploid organiams carry ___ copies of each gene

A

two

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11
Q

how are gametes haploid

A
  • diploid orgs carry 2 copies of each gene – one on each homologous chromosome
  • alleles are segregated during meiosis
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12
Q

when sperm and ovum fuse in fertilisation they form a?

A

single diploid cell – zygote

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13
Q

homozygous vs heterozygous definition

A

homo: sperm and egg carry same allele for particular gene

hetero: different alleles

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14
Q

phenotype of an individual is determined by?

A

genotype

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14
Q

define phenotype

A

an organisms observable characteristics/traits
- including morphology and biochemical properties

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15
Q

define genotype in individuals

A

two alleles present in an organism for a particular gene

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16
Q

what is a carrier (genotypes)

A

an individual with a recessive allele of a gene with no effect on phenotype

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17
Q

define gene

A

a piece of DNA containing information about a particular trait

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18
Q

define allele

A

a particular version of a gene

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19
Q

define dominant allele

A

allele that has the same effect on the phenotype whether 1 or 2 copies are present

In heterozygous state: will mask presence of recessive allele

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20
Q

define recessive allele

A

allele that only has an effect on the phenotype when two copies are present (in a homozygous state)

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21
Q

define co-dominant alleles

A

Alleles that jointly affect the phenotype when present together in a heterozygote

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22
Q

define locus

A

the particular position on homologous chromosomes of a gene

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23
Q

what does this mean:
P
F1
F2

A

P = Parental generation
F1 = first filial (offspring) generation
F2: second filial generation – offspring, cross of F1 gen

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24
define autosomal genes
genes on autosomes (non sex chromosomes)
25
sex linked genes
genes on sex chromosomes (X and Y)
26
what is complete dominance?
when the dominant allele masks the recessive allele
27
(in context of genetic diseases) distinguish between rare and recessive alleles
recessive: interaction of allele in diploid state, only affect phenotype when heterozygous rare: frequency of allele -- how many individuals carry it
28
what is a mutagen
any agent that causes or increases the frequency of mutations by triggering changes in the genetic material of an organism
29
examples of mutagens
radiation, chemicals (Eg from cigarette smoke)
30
mutagens vs carcingogens
carcinogens are mutagens that can lead to cancer!
31
what is radiation
higher level radiation (ionising radiation) can break bonds between atoms incl DNA = mutations
32
when does ARS occur
when person is exposed to large dose of ionising radiation
33
what were the consequences of the nuclear bombing of Hiroshima
over 100k ppl died from fires, explosive shockwave, and Acute Radiation Syndrome (ARS)
34
effects of lower vs larger vs very high doses of radiation
low: nausea, headache larger: seizures, fever very high: death incr risk of cancer
35
what was the chernobyl accident 1986?
accidental nuclear core explosion at chernobyl power station in ukraine
36
how did the radiation from chernobyl lead to an increased rate of thyroid cancer in children 3
1. a radioactive isotope released was iodine-131 2. thyroid gland incorporates iodine into some hormones it produces 3. radioactive iodine incorporated into thyroid hormones = incr rate of mutation
37
how was the radiation of the chernobyl site limited
concrete cover (new cover needed in 2016)
38
what kind of genetic disease is cystic fibrosis
autosomal recessive
39
how does the recessive allele in cystic fibrosis cause it
mutation in cystic fibrosis transmembrane conductance regulatory gene (CFTR) (a gene in chormosome 7) which codes for a chloride channel in mucous membranes
40
effects of cystic fibrosis
altered mucus buildup in lungs = dangerous infections + damage to lung tissue + mucus builds up in liver and pancreas =affects digestion
41
what kind of genetic disease is sickle cell anemia
autosomal co-dominant
42
how is the sickle cell anemia genotype presented in diagram
Hb^aHb^s = carrier
43
what kind of genetic disease is Huntington's disease
autosomal dominant
44
what is huntington's disease
neurodegenerative disorder that manifests ppl 30-50 of age
45
what is huntington's disease caused by
dominant allele is mutation of Huntingtin (HTT) gene on chromosome 4
46
symptoms of Huntington's disease
loss of muscle coordination, cognitive delcine, psychiatric problems
47
how many years life expectancy after huntingtons disease symptoms are observed
10 years
48
how common is the gene for huntingtons disease
1 in 10 000
49
how are blood group alleles presented
I^A I^B i
50
genotype for B blood
I^BI^B or I^Bi
51
alleles I^A and I^B are __________
codominant
52
what does the I in the alleles of blood. groups stand for
isoagglutinogen
53
whats the difference between IA and IB and i (blood groups)
same base molecule BUT different additions to the molecule by A and B additions: antigens A: N-acetylegalactosamine B: galactose
54
how are linked genes shown (Eg on X and Y)
as a superscript to the letter
55
what is haemophilia
genetic disorder where blood clotting is impaired (formation of blood clot controlled by cascade of coagulation factors whose genes are located on X chromosome)
56
what component in blood clotting is affected by haemophilia
fibrin formation is prevented
57
how are haemophilia alleles presented
Xᴴ = unaffected Xʰ = haemophilia
58
what is red green colourblindness
individual fails to differentiate red and green
59
what is red green colour blindness caused by
mutation to red/green retinal photoreceptors -- located on X chromosome
60
how is red-green colour blindess diagnosed
ishihara colour test
61
how are alleles for colour blindness presented
Xᴬ = unaffected Xᵃ = colour blindness
62
what is a test cross
testing a suspected heterozygote plant/animal by crossing it with a KNOWN HOMOZYGOUS RECESSIVE
63
how to calculate probability of 2 independent events occuring
multiply
64
how to calculate probility that one event or another occurs
add
65
the larger the sample size, the ______ the difference between observed and expected outcomes
smaller
66
what are pedigree charts used for (those circle square family tree things)
demonstrate a particular type of inheritance, deduce pattern of genetic disease inheritance
67
how to identify autosomal dominant when analysing a pedigree
every affected individual has at least 1 affected parent both males and females affected every generation
68
how to identify autosomal recessive when analysing a pedigree
both m and f affected 2 unaffected can have affected child skips generations
69
how to identify sex-linkage in pedigree charts
usually only males affected sometimes females affected only when father is affected

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