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Biology A level > 4.3 Inheritance > Flashcards

4.3 Inheritance Flashcards

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1
Q

What is the definition of allele?

A

Variations of the same gene

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2
Q

What is the definition of gene?

A

A section of DNA that codes for a polypeptide

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3
Q

What is the definition of dominant?

A

Will be expressed in even when heterozygous

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4
Q

What is the definition of recessive?

A

Only expressed when homozygous

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5
Q

What is the definition of phenotype?

A

Physical expression of a gene

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6
Q

What is the definition of genotype?

A

Combination of alleles

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7
Q

What is the definition of homozygous?

A

Alleles for a characteristic are the same

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8
Q

What is the definition of heterozygous?

A

Alleles for a characteristic that are different

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9
Q

What is Mendals first law?

A

Law of segregation
All characteristics are determined by alleles tat occur in pairs
only one form each pair can be present in a single gene

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10
Q

What is Mendals second law?

A

Law of independent assortment
Each pair of alleles may combine randomly with either of another pair

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11
Q

What is Dihybrid inheritance?

A

The simultaneous inheritance of two alleles determined by two genes on different chromosomes

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12
Q

What ratio did Mendal conclude for F2?

A

9:3:3:1

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13
Q

What is a test cross?

A

Crossing dominant phenotypes wit homozygous recessive

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14
Q

When is H0 rejected?

A

If the result exceeds the critical value and is therefore significant

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15
Q

What are the exceptions to mendals law?

A

Co-dominant alleles
Sex linked genes
Non independent assortment

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16
Q

What is sex linkage?

A

Alleles linked to the X or Y chromosome

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17
Q

What are some examples of sex linked diseases?

A

Red/green colour blindness
Haemophilia

18
Q

What is codominance?

A

When alleles are expressed equally in the phenotype (e.g. Red, pink and white)

19
Q

What us a mutation?

A

a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide

20
Q

What is an ancogene?

A

A mutation allowing cells to divide uncontrollably

21
Q

What is a mutagen?

A

A factor causing a mutation

22
Q

What is a Insertion/deletion mutations? And what is it impact?

A

When 1 or more nucleotide pairs are inserted or deleted from the sequence
Causes a frameshift in the sequence of nucleotides

23
Q

What is point mutation/substitution?

A

where one base pair is replaced by another

24
Q

What is an Oncogene?

A

A gene that can develop into a tumor

25
Q

What is the impact of cancer to the body?

A

Inhibited bodily functions

26
Q

What is the impact of cancer to the body?

A

Inhibited bodily functions

27
Q

How is sickle cell anaemia caused?

A

A gene mutation to the gene producing haemoglobin
Glutamic acid is replaced with valine
Polypeptide chain is altered producing Haemoglobin S

28
Q

How is sickle cell anaemia inherited?

A

Mutated gene is codominant
Homozygous = sufferer
Heterozygous= 30-40% chance of suffering

29
Q

What are the symptoms of sickle cell?

A

RBC carrying capacity decreased
joint pain
organ damage
distorted blood vessels

30
Q

What is a silent mutation?

A

Multiple codons for 1 amino acid so sequence changes but not amino acid produced

31
Q

What is epigenetics?

A

Control of gene expression with factors outside of sequencing

32
Q

What is methylation of cytosine?

A

Histone modification after translation nucleosomes pack less tightly making histones more accessible and therefore more transcription occurs

33
Q

What are the consequences of epigenetic changes?

A

genomic imprinting
x inactivation

34
Q

What is genomic imprinting?

A

Inactivation of a gene/genes passed down generations leading to permeant switching off and genetic conditions

35
Q

What is X inactivation?

A

Whole chromosome inactivation
cells of female mamals will use only one X chromone and the other dense chromatin Barr body

36
Q

What does epigenetics control?

A

How likely transcriptions are
Post transcription alterations

37
Q

What factors impact epigenetics?

A

Lifestyle
mental health
Physical health
Weather
chemical or biological exposure

38
Q

What is an epigenome?

A

The accumulation of environmental signals received in life

39
Q

What is Hyper-methylation?

A

Tumour suppressant inhibited
so no control of tumour growth

40
Q

What is hypo-methylation?

A

lack of methylation

41
Q

What is hypo-methylation?

A

lack of methylation

42
Q

What is hypo-methylation?

A

lack of methylation

Biology A level (15 decks)

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