Inheritance Flashcards

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1
Q

How many chromosomes does the average human body cell contain?

A

46
Or 23 pairs

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2
Q

How many chromosomes does the average human gamete contain?

A

23

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3
Q

Mitosis

A

Splitting of human body cells into 2 genetically identical daughter cells

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4
Q

Why does mitosis occur?

A

For growth, repair and development of tissue

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5
Q

Meiosis

A

Splitting of gametes to make 4 genetically different daughter cells

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6
Q

Where does meiosis take place

A

Reproductive organs
Testes/ovaries

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7
Q

Chromosome

A

Long threads that contain the molecule DNA

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8
Q

How are chromosomes in a diploid cell?

A

Each normal human body cell has 23 chromosomes
And also a copy of that cell
1 copy from the mother
And another from the father
So 46 in total

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9
Q

How are chromosomes in a haploid cell?

A

Only 23 chromosomes with no copies from parents
As they are a mix of parents dna to form your own
Because haploid cells = gametes

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10
Q

What is the structure of DNA called?

A

Double helix

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11
Q

Gene

A

Small section of DNA in a chromosome

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12
Q

How do genes work?

A

They have amino acids
That encode for a specific sequence to make a specific protein that determines an inherited characteristic

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13
Q

Stages of meiosis

A

Diploid cell in reproductive organs
Replicates copies of chromosomes
The DNA sections get swapped = variation
Divide once
Divide again = 4 different gametes

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14
Q

What happens in fertilisation

A

The sperm and egg with 23 chromosomes each combine
So makes a diploid cell with 23 pairs or 46 in total
So a pair has one chromosome from the mother and the other from the father

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15
Q

What happens after fertilisation?

A

Fertilised cell divides by MITOSIS
and creates a clump of identical cells = embryo
The cells then differentiate into different types of cells eg muscle and nerve cells

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16
Q

What are the contents of the double helix?

A

2 strands which are polymers
Joined together by small molecules
And wrapped around each other

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17
Q

Chromosome pairs

A

1 from the mother and the other for the father
Contain 2 copies of every gene therefore codes for the same characteristic

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18
Q

Genome

A

Entire genetic material of an organism

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19
Q

Benefits of studying human genome

A

Can search for genes linked to inherited diseases
Understand and treat hereditary diseases
Trace human migration patterns from the past / discover ancestry

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20
Q

What are the molecules DNA is a polymer of?

A

Nucleotides

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21
Q

What are nucleotides made of?

A

Phosphate group (circle)
Sugar molecule (pentagon)
Base (rectangle)

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22
Q

What changes and stays the same in nucleotides?

A

Phosphate (circle) and sugar ALWAYS STAY THE SAME
however the base molecule has 4 different types

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23
Q

4 different types of base molecules

A

A, C, G, T

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24
Q

What are the different nucleotides DNA contains?

A

Phosphate + sugar + A
Phosphate + sugar + C
Phosphate + sugar + G
Phosphate + sugar + T

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25
Q

How do strands of DNA look in terms of nucleotides?

A

Phosphates on the outside
Then sugars
And the base facing inside
This is mirrored for the 2nd strand
There are many rows of these

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26
Q

How are the bases paired?

A

They are complementary meaning the same bases pair on opposite strands
A with T
C with G

27
Q

What is base C linked to?

A

Base G

28
Q

What is base G linked to?

A

Base C

29
Q

What is base A linked to?

A

Base T

30
Q

What is base T linked to?

A

Base A

31
Q

What are proteins made of?

A

Long chains of amino acids
Polymers

32
Q

What determines a proteins function?

A

The amino acids order determines the proteins shape
And the shape of the protein determines its function
Such as being an enzyme or hormone

33
Q

What determines the amino acids?
Rate the rizzness

A

Bases that are read in triplets determine a specific amino acid

34
Q

How do bases code for specific amino acids?

A

The cell reads the DNA sequence of the bases in triplets
Eg ATG GGA CGC ATA
Each of these triplets encodes for a specific amino acid in the protein

35
Q

Stage 1of protein synthesis

A

Transcription

36
Q

Where does stage 1 of protein synthesis (transcription) take place?

A

In the nucleus

37
Q

Events of transcription

A

Base sequence of the gene is copied into a ‘template’ molecule called mRNA
Which is single strand molecule
mRNA passes out of the nucleus

38
Q

Stage 2 of protein synthesis name

A

Translation

39
Q

Where does stage 2 of protein synthesis (translation) take place?

A

Cytoplasm

40
Q

Events of translation

A

mRNA now in the cytoplasm
It attaches to a ribosome
Amino acids are bought to the ribosome on carrier molecules called tRNA
The ribosome reads the triplets of bases
And carries the correct amino acids into correct order
Thus creating the right protein chain for its right shape and function ie enzyme

41
Q

What is the point of protein synthesis?

A

Creating the right protein by changing the order of amino acids for its specific purpose

42
Q

Mutation

A

Caused by a change in base sequence so it encodes different amino acids which makes a different shape and different protein
Happens all the time

43
Q

Do a change in amino acid sequence always cause a new protein/ mutation?

A

NO because different base triplets can encode for the same amino acid
Ie ACG AND TTC could code for the same amino acid
Therefore there is no effect on function of protein

44
Q

What happens if a mutation does have an effect?

A

A different amino acid would have been coded for
And so the protein like an enzyme changes shape
So potentially it’s active site changes

45
Q

What else do chromosomes contain?

A

Non coding parts of DNA
That can control and stop genes from producing proteins

46
Q

Why do mutations occur?

A

If the non coding region of chromosome has a gene turned on when it should be off
It will produce a protein that shouldn’t be there
This could have a bad effect on a cell like uncontrolled mitosis = cancer

47
Q

Alleles

A

Different versions of genes that code for different characteristics

48
Q

Genotype

A

Tells us the alleles present
Ie XX or XY

49
Q

Homozygous

A

2 copies of the same allele
Like XX
Homo = same

50
Q

Phenotype

A

The characteristic as a result of the genotype

51
Q

Heterozygous

A

2 different alleles
Like XY
Herero = different

52
Q

Dominant allele

A

It will show in the phenotype even if there’s only one copy
Like XY
The Y is dominant here
This therefore will give decide someone’s phenotype even if it’s heterozygous

53
Q

Recessive allele

A

Only shows in phenotype if there are 2 copies present
Like XX
The x is usually recessive because if it’s XY it will be a male but because there’s 2 it will be a female

54
Q

What is Cystic fibrosis ?

A

Disorder of cell membranes

55
Q

How is cystic fibrosis inherited?

A

Allele for normal cell function is dominant = C
Allele for cystic fibrosis is recessive = c
Therefore you have to have 2 copies of this aka cc to inherit it

56
Q

Carrier

A

Someone who carries the dominant allele for a characteristic

57
Q

Polydactyly

A

Disorder with extra fingers or toes

58
Q

How is polydactyly inherited?

A

A dominant allele
So only having one of them will express the disorder, despite having the allele for normal one

59
Q

Is it possible to be a carrier of polydactyly?

A

No because it’s caused by a dominant allele so just having 1 = expressed

60
Q

How to prevent inherited disorders?

A

Embryo screening to look for them
Potentially = gene therapy by correcting alleles

61
Q

Embryo screening

A

Checking to see if they have alleles present for disorder
And implanting ones without it into mother

62
Q

Issues with embryo expensive

A

Too expensive
Many embryos destroyed which is seen as unethical
Slippery slope that it may result in screening for specific characteristics

63
Q

What determines the sex of an offspring?

A

The 23rd pair of chromosomes
One from mother XX and one from father XY