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Biology 101 > genetics > Flashcards

genetics Flashcards

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1
Q

what is genetics

A

Examines how DNA sequences in chromosomes (genes) result in different traits (phenotypes)
Studies how genes & traits are passed on from one generation to another
i.e. the study of heredity

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2
Q

what did gregor mendel do?

A

performed genetic crosses in peas and observed they have specific traits in specific pattern (either or)
either purple or white
wrinkled or smooth

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3
Q

what is a cross

A

it is mating, pairing specific parents with specific traits to produce off spring

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4
Q

what is a pure breeding plant (pure strain)

A

plant wheree all their ancestors showed the same traits 100% of the time.

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5
Q

define phenotype

A

observable characteristics based on genotype

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6
Q

define genotypee

A

set of genes in a organism (responsible for its traits)

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7
Q

what are true breeding parents called

A

the P generation

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8
Q

what are the offspring of those parents called

A

f1 generation (filial or child)

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9
Q

what are the offspring of f1 and f1 called?

A

F2 generation

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10
Q

what is it called when you cross two different true breeding varieties

A

hybridization

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11
Q

menders experiment purple vs white flowers:explain

A

mendel cross bred pure breeding purple and white flowers
used pollen from white to fertilize purple eggs
result : all f1 hybrids have purple flowers
same result when pollen from purple and eggs from white was used

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12
Q

what is the result of menders experiment

A

all offspring f1 have purple flowers regardless of having one white and one purple parent

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13
Q

what is the law of segregation

A

Each gamete only carries 1 copy (allele) of each gene (since only have 1 copy of each chromosome)
Lets call our flower colour gene ‘A’ for simplicity
Fuse 2 haploid gametes to form 1 diploid zygote
Each zygote (each F1 plant) will have 2 copies of each gene – 1 from each parent
Each F1 plant will have 1 purple allele & 1 white allele

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14
Q

define allele

A

different versions of the same gene

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15
Q

explain why all f1 offspring of purple and white flowers were purple

A 
because purple (A) is dominant over white (a) 
therefore wherever purple shows up it will mask white
consequently white is recessive: will not show up alongside purple
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16
Q

explain second part of mendels experiment

A

cross breeds f1xf1

offspring shows both purple and white in a 3;1 RATIO\

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17
Q

what is the locus of an allele

A

the location of the gene

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18
Q

what is homozygous

A

Both alleles at a locus are the same

e.g. AA or aa

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19
Q

what is heterozygous

A

The 2 alleles at a locus are different

e.g. Aa

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20
Q

what are menders 4 concepts

A

Different alleles account for variations in inherited characters

For each character an organism inherits 2 alleles; 1 from each parent

if the 2 alleles at a locus differ, the dominant allele determines the organism’s appearance
The recessive allele has no noticeable effect on the organism’s appearance

Law of segregation
2 alleles for a heritable character separate (segregate) during gamete formation & end up in different gametes

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21
Q

what is you are testing more than one gene?

A

dihybrid crosses

22
Q

how do you do dihybrid?

A

FOIL TRAITS

23
Q

WHAT are the two assortment hypotheses

A

Independent assortment
Genes (& corresponding characteristics) associate separately
In a gamete, receiving a certain allele for a gene does not influence which allele is received for a different gene*

Dependent assortment
Genes (& corresponding characteristics) associate together

24
Q

what phenotypic ration does independent assortment result in

A

9:3:3:1

25
Q

multiplication rule?

A

Probability of 2 or more independent events occurring together is calculated by multiplying the probability of each event.
Key word: “And”

26
Q

addition rule?

A

Probability of 2 or more mutually exclusive events is calculated by adding their probabilities.
Key words: “Either” “Or”

27
Q

what are the 5 inheritance patterns

A 
autosomal recessive
autosomal dominant
x linked recessive
x linked dominant
y linked
28
Q

explain autosomal recessive

A

equal freq in sexes, skips generations, affected offspring born to unaffected parents

29
Q

explain autosomal dominant

A

equal freq in sexes, both sexes transmit to offspring, does not skip gens, unaffected parents do not transmit

30
Q

x linked recessive

A

males>females affected
affected sons born to unaffected mothers,
never passes from father to son

31
Q

x linked dominant

A

females > malees

does not skip gens

32
Q

y linked

A

only males affected
passed from father to son
does not skip gens

33
Q

what gender are sex linked genes more phenotypically expressed?

A

males

34
Q

females and their x chromos

A

inherit two x chromosomes therefore would need two copies of the recessive allele to show recessive phenotype

35
Q

males and their xy chromos

A

nothing can mask the recessive x linked gene

36
Q

examples of sex linked x traits

A

eye colour
colour blindness
haemophilia

37
Q

what are the three types of dominance

A

complete dominance
incomplete dominance
co-dominance

38
Q

explain complete domincance

A

phenotypes of heterosexuals zygote and dominant homo are identical

39
Q

explain incomplete dominance

A

2 difference alleles for 1 gene are BOTH expressed (intermediate) not an exact blend
something shows through for both

40
Q

explain co-dominance

A

2 different alleles for 1 gene are BOTH FULLY expressed

41
Q

define epistasis

A

A gene at one locus alters the phenotypic expression of a gene at a different locus

42
Q

define pleotropy

A

A single mutation that has multiple effects (produces multiple phenotypes)

43
Q

define neomorphy

A

A mutation causes altered function - either expression at a different place or time, or a novel (new) function\

44
Q

define multifactorial

A

a trait is influenced by multiple phenotypes and environmental factors

45
Q

define polygenic

A

a trait is influenced by multiple genes

46
Q

what is the epistatic gene

A

thee gene that is responsible for masking/supressing

THINK DOG EEXAMPLE THERE IS A PATHWAY HAS TO GO THROUGH EPISTATIC GENE FIRST

47
Q

explain pleiotropy

A

1 gene is associated with many traits because genes are often active in many plaecees
eex: sickle cell anemia and albinism

48
Q

give an example of multifactorial traits

A

height and heart disease/cancer

49
Q

explain polygenic traits

A

you will see an additive affect off different alleles/genes

either you will have an additive or no

50
Q

penetrance and expressivity

A

Penetrance
Proportion of individuals of a certain mutant genotype that exhibit the mutant phenotype
Quantitative
Depends on modifiers, epistasis, & environment

Expressivity
Severity of the mutant phenotype generated by a particular allele
Qualitative
Depends on genetic background & environment

51
Q

explain x inactivation

A

Females condense & (almost completely) de-activate 1 of their 2 X-chromosomes during early embryonic development
Barr-body = condensed X chromosome
Normal females will have 1 barr-body & 1 uncondensed X chromosome per cell
Normal males will not have barr-bodies

52
Q

what is lyon hypothesis

A

Females are mosaics
Which X chromosome becomes a barr-body is initially random
Humans: occurs at about day 10
Daughter cells will inherit the same pattern of inactivation expressed by the original cell

Biology 101 (15 decks)

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