Week 2 Flashcards

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1
Q

What is codominance?

A

The full effect of both alleles can be seen in the phenotype of the heterozygote

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2
Q

What is a biochemical pathway?

A

Shows the different mutant strains and the supplements in the order from which all strains are blocked to all being active

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3
Q

Define incomplete dominance

A

Heterozygote is a blended colour

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4
Q

Define codominance

A

The effect of each allele can be seen in the heterozygote

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5
Q

Define prototroph

A

An organism that can grow on minimal media

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6
Q

Define auxitroph

A

An organism that requires a supplement to grow on minimal media

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7
Q

What is a reciprocal cross?

A

A second cross between a male of phenotype a and a female of phenotype b as well as a male of phenotype b and a female of phenotype a to determine sex or autosomal linkage

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8
Q

What is a metabolic pathway?

A

Chemical reactions in cells that occur in a step by step sequence

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9
Q

What is a metabolic block?

A

A block in metabolic pathway that prevents the natural production of an enzyme from occurring

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10
Q

What is a phenocopy?

A

A copy of an inherited condition that occurs from an environmental cause

E.g meromelia- limblessness, a phenocopy of this inherited disease occurs from taking thalidomide during pregnancy

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11
Q

What is pleitropy?

A

A single gene may affect many features of a phenotype

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12
Q

What is variable expression

A

Degree/ range in which a particular phenotype is expressed by individuals
E.g mild, moderate and severe

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13
Q

What is reduced penetrance?

A

The proportion of genotypes that show the expected phenotype

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14
Q

What is a lethal allele genotype mutation?

A

An allele genotype or mutation that results in death( may be lethal at different stages of development)

Recessive Lethal: death in homozygous state
Dominant lethal: death in homozygous and heterozygous state

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15
Q

What is a Karyotype?

A

Sorted chromosome sets

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16
Q

What is a karyogram?

A

A drawing of chromosomes with banding shown

17
Q

What is aneuploidy?

A

Extra chromosomes but not a set

E.g trisomy 2N+1/2N-1

18
Q

What is euploidy?

A

Extra sets of chromosomes

Polyploidy: 3N triploid, 4N tetraploid

19
Q

What are the two types of chromosomes?

A
  • autosomes

- sex chromosomes

20
Q

What are the five sex determining mechanisms?

A

1 environment(sex determined at conception(
2 genes (sex may be altered after conception)
3 haplo/diploidy
4 balance of autosome to sex chromosomes
5 sex chromosomes

21
Q

What are some examples of environmental sex determination?

A

Reptiles:
- temperatures of nest affect the proportion of males to females, the higher the temp the more males

Bonelia:
- the closer the offspring land to the proboscis of worm, the more likely they are to be male.

22
Q

What is an example of genetic sex determination?

A

Drosophila
- particular genotype may change expected phenotype

While xx= female and xy= male
Change to mutant at transformer locus can change female phenotype/ lack of tra+/ presence of tra allele prevents expression of female phenotype

Therefore
Tra Tra; XX= phenotypically male
Tra Tra: XY= genetically male

23
Q

What is an example of haplo/diploidy?

A

Honey bees

Females are diploid(2N) from fertilised eggs

Males are Haploid (N) from unfertilised eggs
Male is hemizygous because only has one allele at each locus

24
Q

What is an example of sex chromosomes to autosome sex determination?

A

Drosophila:
Relies on the ratio of sex chromosomes to autosomes

Female= AAXX= 1
Male= AAX= 1/2
25
Q

What is an example of sex chromosomes sex determination?

A

Humans

Have two sex chromosomes that determine gender

X & Y

XX= female

XY= male

26
Q

Define hemizygous

A

A sex linked trait where only one copy of an allele is present

E.g x linked traits in human males is hemizygous

27
Q

Define heterogametic

A

Produces two different types of gametes with respect to sex

28
Q

Define homogametic

A

Produces one type of gamete with respect to sex