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Biology > Variation, Genetics and Inheritance > Flashcards

Variation, Genetics and Inheritance Flashcards

1
Q

What is a mutation

A

A random change in an organisms DNA

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2
Q

What does DNA stand for

A

Deoxyribonucleic acid

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3
Q

What shape are DNA strands

A

double helix

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4
Q

What is a gene

A

a small section of DNA found on a chromosome

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5
Q

Define genome

A

A geneome is an entire set of genetic material in an organism

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6
Q

Where in a cell is DNA found

A

nucleus

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7
Q

How does a gene help a cell to make a specific protein

A

each gene codes for a particular sequence of amino acids which are put together to make a specific protein

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8
Q

What 3 things does a nucleotide consist of

A

sugar, phospate and a base

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9
Q

what are the 4 different bases

A

A,T,C,G

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10
Q

Which bases pair with eachother

A

A+T G+C

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11
Q

Give one function of non-coding parts of DNA

A

they control whether or not a gene is expressed

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12
Q

Where are proteins assembled

A

Made in the ribosomes

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13
Q

What happens when a protein chain is complete

A

It folds into a unique shape which allows the protein to perform a task its meant to do.

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14
Q

Function of enzymes

A

used as a catalyst to speed up chemical reactions in the body

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15
Q

Function of hormones

A

used to carry messages around the body

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16
Q

What do carrier molecules do

A

Bring the correct amino acids to the ribosomes in the correct order

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17
Q

do mutations occur continuously

A

yes

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18
Q

What do mutations do

A

change the sequence of DNA bases in a gene, which produces a different form of the gene.

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19
Q

What are the 3 types of mutation

A

Insertions
Deletions
Substitutions

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20
Q

Explain Insertion mutations

A

where a new base is inserted into the DNA base sequence where it shouldn’t be.

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21
Q

Explain Deletion mutations

A

When a random base is deleted from the DNA base sequence.

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22
Q

Explain substitution mutations

A

when a random base in the DNA base sequence is changed to a different base

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23
Q

Define sexual reproduction

A

where genetic information from two organisms (mother and father) is combined to produce offspring which are genetically different to either parent,

24
Q

How many chromosomes does a human gamete contain

A

23

25
Q

What are the male and female gametes

A

MALE- sperm cell
FEMALE- egg cell

26
Q

What is fertilisation

A

the fusion of gametes

27
Q

Expalain fertlisation in humans

A

The egg cell (from the mother) and the sperm cell (from the father) fuse together to form a cell with the full number of chromosomes (46)

28
Q

Why are the parents offspring genetically different

A

because there are two parents, the offspring contain a mixture of their parents’ genes

29
Q

Briefly explain asexual reproduction

A

In asexual roproduction there is only one parent. There is no fusion of gametes, no mixing of chromosomes and no genetic variation between plant and offspring meaning that the offspring are genetically identical to the parent.

30
Q

What are the 5 steps of meiosis

A
  1. Cell duplicates its genetic information forming two chromosomes
  2. In the first division in meiosis the chromosome pairs line up in the center of the cell
  3. The pairs are then pulled apart so each new cell has one copy of each chromosome.
  4. In the second division, the chromosomes line up again in the centre of the cell. They are then pulled apart
  5. You then get 4 gametes, each with a single set of chromosomes in it.
31
Q

How many chromosomes are in a human cell

A

46

32
Q

advantage of sexual reproduction

A

Variation in the offspring increases chances of surviving a chaange in the environment

33
Q

advantage of asexual reproduction

A

One parent so uses less energy and is faster

34
Q

What chromosomes do males have

A

X AND Y

35
Q

What chromosomes do females have

A

two X chromosomes

36
Q

Define allele

A

Different forms of a single gene

37
Q

Define recessive

A

The allele that only has an effect when the genotype is homozygous

38
Q

Define dominant

A

The allele that has an effect in either homozygous or heterozygous state

39
Q

Define genotype

A

the genes an organism contains

40
Q

Define phenotype

A

an organisms appearence or characteristic

41
Q

Define homozygous

A

Having two identical alleles for a particular gene

42
Q

Define heterozyggous

A

having two different alleles for a particular gene

43
Q

What is cystic fibrosis

A

an inherited disorder of the cell membranes, whch results in the body producing lots of mucus in the air passages and in the pancreas

44
Q

What are the symptoms of cystic fibrosis

A

difficulty breathing

45
Q

Is cystic fibrosis carried by a dominant or recessive allele

A

recessive

46
Q

What is polydactyly

A

An inherited disorder where a baby is born with an extra digit

47
Q

Is polydactyly carried by a dominant or recessive allele

A

dominant- if one parent has that allele it can be inherited

48
Q

What is embryonic screening

A

A way of detecting inherited disorders such as cystic fibrosis in embryos.

49
Q

What are the two different ways of embryo screening

A

PGD (pre implantation genetic diagnosis) CVS (Chorionic villius sampling)

50
Q

Explain PGD

A

During IVF, embryos are fertilised in a lab and then implanted into the mothers womb. Befoore being implanted, its possible to remove a cell from the embryo to analyse genes. Embryos with healthy alleles will be implanted into the mother and embryos with unhealthy alleles will be destroyed.

51
Q

Explain CVS

A

CVS is usually carried out between 10 and 13 weeks of pregnancy. It involves taking a sample of cells from part of the placenta and analysing their genes. If the embryo is found to have an inherited disorder, the parents can decide if they want to terminate the pregnancy

52
Q

3 Arguments for embryonic screening

A
  • Helps to stop people suffering from inherited disorders.
    -Treating disorders costs lots of money, so screening the embryos could reduce healthcare costs
    -Gives parents a choice if they want to terminate a pregnancy
53
Q

3 Arguments against embryonic screening

A
  • May become a point where everyone wants to screen their embryos so they can pick the most desireable one.
    -Expensive
    -There is a risk that CVS could cause a miscarriage
54
Q

Examples of genetic variation

A

Eye colour
Blood group
Flower colour

55
Q

Examples of environmental variation

A

Weight
Accent

56
Q

Examples of environmental and genetic variation

A

Height
Intelligence
Health

Biology (16 decks)

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