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Bio > 6.2 > Flashcards

6.2 Flashcards

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Biology 101 flashcards
1
Q

What is a genotype?

A

Genetic makeup of an organism

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2
Q

What is a phenotype?

A

Visible characteristics of an organism

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3
Q

What chromosome mutations may occur during meiosis?

A
  • Deletion -> part of chromosome with genes and regulatory sequence is lost
  • Inversion -> section of chromosome may break off and rotate 180 degrees
  • Translocation -> piece of chromosome which breaks off and attaches to another
  • Duplication -> chromosome duplicated
  • non-disjunction -> pair of chromosomes or chromatids fail to separate
  • Aneuploidy -> chromosome not exact multiple of haploid number for organism
  • Polyploidy -> diploid gamete fertilised by haploid gamete
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4
Q

How does sexual reproduction cause genetic variation?

A
  • Allele shuffling during crossing over of prophase 1
  • Independent assortment of chromosomes during metaphase/ anaphase 1
  • Independent assortment of chromatids during metaphase/anaphase 2
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5
Q

Example of an environmental factor affecting plant gene expression?

A

Plants kept in dim light after germination or soil with little magnesium ions can not develop chlorophyll becoming yellow-white.

Chlorotic plants (chlorosis)

Can not photosynthesise

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6
Q

What is an allele?

A

A version of a gene

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7
Q

Define hetrozygous.

A
  • Not true breeding

- Having two different alleles at a specific gene locus on pair of homologous chromosomes

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8
Q

Define homozygous.

A
  • True breeding

- Having identical alleles at a particular gene locus on pair of homologous chromosomes

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9
Q

Define monogenic.

A

Determined by single gene.

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10
Q

What are features of monohybrid cross and ratio produced?

A
  • Two parent strains with different phenotypes that are both true breed (homozygous) (TT and tt) crossed
  • F1 generation identical to one phenotype parent (Tt)
  • F1 self fertilise
  • F2 generation 3:1 ratio produced (TT, Tt, Tt, tt)
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11
Q

What is a test cross used for and how would it be used?

A
  • Used to identify genotype
  • Organism with unknown dominant genotype (TT, Tt) crossed with recessive homozygous genotype
  • If generation produced has phenotype of recessive genotype then genotype of unknown is dominant heterozygous
  • If all generation shows dominant phenotype then unknown genotype is homozygous dominant
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12
Q

Define dihybrid.

A

Involving two gene loci

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13
Q

What are features of dihybrid cross and ratio produced and what did Mendel deduce from this?

A
  • Parent genotypes are heterozygous dihybrids (YYRR, yyrr)
  • F1 generation will be heterozygous dihybrid
  • F1 gametes all have different genotypes
  • F2 ratio produced 9:3:3:1
  • Alleles of two gene locus inherit independently of each other, each gamete has one allele for each locus
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14
Q

Define co-dominance.

A

Where both alleles present in genotype of heterozygous individual contribute to individual phenotype

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15
Q

Define multiple alleles.

A

Characteristics for which there are more then three alleles in the populations gene pool

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16
Q

What are I-A and I-B dominant to?

A

I-A and I-B are dominant to I-O

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17
Q

What are the four genotypes for blood groups in humans?

A

I-A
I-O
I-B

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18
Q 
Answer the following:
I-A + I-A=
I-A + I-O=
I-B + I-B=
I-B + I-O=
I-O + I-O=
I-A + I-B+
A

1) I-A, I-A (Blood group A)
2) I-A, I-O (Blood group A)
3) I-B, I-B (Blood group B)
4) I-B, I-O (Blood group B)
5) I-O, I-O (Blood group O)
6) I-A, I-B (Blood group AB)

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19
Q

Define sex-linked.

A

Gene present on one of sex chromosome.

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20
Q

What are the sex chromosomes found in men and women?

A

Female = XX

Male = XY

21
Q

What is the feature of Male sex chromosomes when it comes to genetic diseases (Faulty genes)?

A

Men are functionally haploid for X-linked genes, they can not be hetro or homozygous.

If they inherit faulty gene on X chromosome they will suffer its effects where as women have two X chromosomes therefore if gene faulty on one chromosome it will be functioning on the other

22
Q

What are genetic disorders caused in humans as a result of being sex-linked?

A

Haemophilia A

Colour blindness

23
Q

Define autosomal linkage.

A

Gene loci present on same autosome are inherited together.

24
Q

What does linked genes mean?

A

Linked genes is when a chromosome has two or more of the same gene loci.

25
Q

What ratio is expected from linked gene inheritance where no crossing over has occurred?

A

3:1

26
Q

At what stage do recombinant DNA form?

A

Prophase 1

27
Q

What is epistasis?

A

Interaction of non-linked gene loci which masks the expression of the other.

28
Q

What is effect of epistasis on F2 generation?

A

Decreases genetic variation.

29
Q

What is chi-squared test?

A

Statistical test that is designed to find out if difference between observed and expected data is significant or due to chance.

30
Q

When can we use chi-squared test?

A
  • When data is in categories and not continuous
  • Strong biological theory to use predicted values
  • Sample size is large
  • Data is only raw counts
  • No zero scores
31
Q

What is the null hypothesis?

A

There is no statistically significant difference between observed and expected data. Any difference is due to chance.

32
Q

What is the chi-squared test formula?

A

Sum of (O-E)^2 / E

33
Q

When do we accept null hypothesis?

A

When chi squared result is less then critical value which is at 5%

34
Q

How do we calculate degrees of freedom?

A

Categories - 1

35
Q

Define continuous variation.

A

Variation that produces phenotypic variation where the quantitative traits vary by very small amounts between one group and the next.

  • Usually caused by monogenic
36
Q

Define discontinuous variation.

A

Genetic variation producing discrete phenotypes- two or more non-overlapping categories.

  • Usually caused by polygenic
37
Q

Define directional selection.

A

Natural selection that occurs when an environmental change favours a new phenotype, causing change in population mean.

38
Q

What is the founder effect?

A

Small sample of original population establishes in new area but does not have a gene pool as diverse as the original population.

39
Q

What is a genetic bottle-neck?

A

Large reduction in population size due to environmental catastrophe which also reduces genetic diversity.

40
Q

What is stabilising selection?

A

Natural selection leading to constancy within a population.

Intermediate phenotypes are favoured and extremes are selected against.

Reduces genetic diversity of population.

41
Q

What is difference between genetic drift and genetic bottle neck?

A
  • Genetic drift is when population derives from small number of parents
  • Genetic bottle neck is when population size decreases and then increases again
42
Q

Define population.

A

Members of a species that live in the same place at the same time and can interbreed.

43
Q

What does Hardy-Weinberg principle assume?

A
  • Population is large enough to make sampling error negligible
  • Mating within population occurs at random
  • No selective advantage of any genotype and hence no selection
  • No mutation, genetic drift or migration
44
Q

What is the Hardy-Weinberg formula you need to remember?

A

p^2 + q^2 + 2pq = 1

45
Q

Define allopatric speciation.

A

Formation of two different species from one original species, due to geographical isolation.

46
Q

Define speciation.

A

The splitting of a genetically similar population into two or more populations that undergo genetic differentiation and eventually reproductive isolation, leading to evolution of two or more new species.

47
Q

Define sympatric speciation.

A

Formation of two different species from one original species, due to reproductive isolation, while the populations inhabit the same geographical location.

48
Q

Define artificial selection.

A

Selective breeding of organism, involves humans choosing desired phenotype and interbreeding those phenotype individuals, therefore selecting genotypes that contribute to gene pool of next generation of these organisms.

49
Q

What are Ethical considerations behind artificial selection?

A
  • Domesticated animals retain juvenile characteristics therefore less able to defend themselves
  • Livestock animals with lots of fat and meat succumb to low temperature

Bio (19 decks)

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