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HL Bio > 3.4 inheritance > Flashcards

3.4 inheritance Flashcards

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Biology 101 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
Q

define autosomal genes

A

genes on autosomes (non sex chromosomes)

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25
Q

sex linked genes

A

genes on sex chromosomes (X and Y)

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26
Q

what is complete dominance?

A

when the dominant allele masks the recessive allele

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27
Q

(in context of genetic diseases) distinguish between rare and recessive alleles

A

recessive: interaction of allele in diploid state, only affect phenotype when heterozygous

rare: frequency of allele – how many individuals carry it

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28
Q

what is a mutagen

A

any agent that causes or increases the frequency of mutations by triggering changes in the genetic material of an organism

29
Q

examples of mutagens

A

radiation, chemicals (Eg from cigarette smoke)

30
Q

mutagens vs carcingogens

A

carcinogens are mutagens that can lead to cancer!

31
Q

what is radiation

A

higher level radiation (ionising radiation) can break bonds between atoms incl DNA = mutations

32
Q

when does ARS occur

A

when person is exposed to large dose of ionising radiation

33
Q

what were the consequences of the nuclear bombing of Hiroshima

A

over 100k ppl died from fires, explosive shockwave, and Acute Radiation Syndrome (ARS)

34
Q

effects of lower vs larger vs very high doses of radiation

A

low: nausea, headache
larger: seizures, fever
very high: death

incr risk of cancer

35
Q

what was the chernobyl accident 1986?

A

accidental nuclear core explosion at chernobyl power station in ukraine

36
Q

how did the radiation from chernobyl lead to an increased rate of thyroid cancer in children 3

A
  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
Q

how was the radiation of the chernobyl site limited

A

concrete cover
(new cover needed in 2016)

38
Q

what kind of genetic disease is cystic fibrosis

A

autosomal recessive

39
Q

how does the recessive allele in cystic fibrosis cause it

A

mutation in cystic fibrosis transmembrane conductance regulatory gene (CFTR) (a gene in chormosome 7)

which codes for a chloride channel in mucous membranes

40
Q

effects of cystic fibrosis

A

altered mucus buildup in lungs = dangerous infections + damage to lung tissue
+ mucus builds up in liver and pancreas =affects digestion

41
Q

what kind of genetic disease is sickle cell anemia

A

autosomal co-dominant

42
Q

how is the sickle cell anemia genotype presented in diagram

A

Hb^aHb^s = carrier

43
Q

what kind of genetic disease is Huntington’s disease

A

autosomal dominant

44
Q

what is huntington’s disease

A

neurodegenerative disorder that manifests ppl 30-50 of age

45
Q

what is huntington’s disease caused by

A

dominant allele is mutation of Huntingtin (HTT) gene on chromosome 4

46
Q

symptoms of Huntington’s disease

A

loss of muscle coordination, cognitive delcine, psychiatric problems

47
Q

how many years life expectancy after huntingtons disease symptoms are observed

A

10 years

48
Q

how common is the gene for huntingtons disease

A

1 in 10 000

49
Q

how are blood group alleles presented

A

I^A
I^B
i

50
Q

genotype for B blood

A

I^BI^B or I^Bi

51
Q

alleles I^A and I^B are __________

A

codominant

52
Q

what does the I in the alleles of blood. groups stand for

A

isoagglutinogen

53
Q

whats the difference between IA and IB and i (blood groups)

A

same base molecule BUT different additions to the molecule by A and B

additions: antigens
A: N-acetylegalactosamine
B: galactose

54
Q

how are linked genes shown (Eg on X and Y)

A

as a superscript to the letter

55
Q

what is haemophilia

A

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
Q

what component in blood clotting is affected by haemophilia

A

fibrin formation is prevented

57
Q

how are haemophilia alleles presented

A

Xᴴ = unaffected
Xʰ = haemophilia

58
Q

what is red green colourblindness

A

individual fails to differentiate red and green

59
Q

what is red green colour blindness caused by

A

mutation to red/green retinal photoreceptors – located on X chromosome

60
Q

how is red-green colour blindess diagnosed

A

ishihara colour test

61
Q

how are alleles for colour blindness presented

A

Xᴬ = unaffected
Xᵃ = colour blindness

62
Q

what is a test cross

A

testing a suspected heterozygote plant/animal by crossing it with a KNOWN HOMOZYGOUS RECESSIVE

63
Q

how to calculate probability of 2 independent events occuring

A

multiply

64
Q

how to calculate probility that one event or another occurs

A

add

65
Q

the larger the sample size, the ______ the difference between observed and expected outcomes

A

smaller

66
Q

what are pedigree charts used for (those circle square family tree things)

A

demonstrate a particular type of inheritance, deduce pattern of genetic disease inheritance

67
Q

how to identify autosomal dominant when analysing a pedigree

A

every affected individual has at least 1 affected parent

both males and females affected

every generation

68
Q

how to identify autosomal recessive when analysing a pedigree

A

both m and f affected

2 unaffected can have affected child

skips generations

69
Q

how to identify sex-linkage in pedigree charts

A

usually only males affected

sometimes females affected only when father is affected

HL Bio (53 decks)

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