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Inheritance Flashcards

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
How do strands of DNA look in terms of nucleotides?
Phosphates on the outside Then sugars And the base facing inside This is mirrored for the 2nd strand There are many rows of these
26
How are the bases paired?
They are complementary meaning the same bases pair on opposite strands A with T C with G
27
What is base C linked to?
Base G
28
What is base G linked to?
Base C
29
What is base A linked to?
Base T
30
What is base T linked to?
Base A
31
What are proteins made of?
Long chains of amino acids Polymers
32
What determines a proteins function?
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
What determines the amino acids? Rate the rizzness
Bases that are read in triplets determine a specific amino acid
34
How do bases code for specific amino acids?
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
Stage 1of protein synthesis
Transcription
36
Where does stage 1 of protein synthesis (transcription) take place?
In the nucleus
37
Events of transcription
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
Stage 2 of protein synthesis name
Translation
39
Where does stage 2 of protein synthesis (translation) take place?
Cytoplasm
40
Events of translation
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
What is the point of protein synthesis?
Creating the right protein by changing the order of amino acids for its specific purpose
42
Mutation
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
Do a change in amino acid sequence always cause a new protein/ mutation?
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
What happens if a mutation does have an effect?
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
What else do chromosomes contain?
Non coding parts of DNA That can control and stop genes from producing proteins
46
Why do mutations occur?
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
Alleles
Different versions of genes that code for different characteristics
48
Genotype
Tells us the alleles present Ie XX or XY
49
Homozygous
2 copies of the same allele Like XX Homo = same
50
Phenotype
The characteristic as a result of the genotype
51
Heterozygous
2 different alleles Like XY Herero = different
52
Dominant allele
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
Recessive allele
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
What is Cystic fibrosis ?
Disorder of cell membranes
55
How is cystic fibrosis inherited?
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
Carrier
Someone who carries the dominant allele for a characteristic
57
Polydactyly
Disorder with extra fingers or toes
58
How is polydactyly inherited?
A dominant allele So only having one of them will express the disorder, despite having the allele for normal one
59
Is it possible to be a carrier of polydactyly?
No because it’s caused by a dominant allele so just having 1 = expressed
60
How to prevent inherited disorders?
Embryo screening to look for them Potentially = gene therapy by correcting alleles
61
Embryo screening
Checking to see if they have alleles present for disorder And implanting ones without it into mother
62
Issues with embryo expensive
Too expensive Many embryos destroyed which is seen as unethical Slippery slope that it may result in screening for specific characteristics
63
What determines the sex of an offspring?
The 23rd pair of chromosomes One from mother XX and one from father XY

Biology (55 decks)

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