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Biology > Topic 6 - Inheritance, variation and evolution > Flashcards

Topic 6 - Inheritance, variation and evolution Flashcards

1
Q

What is DNA

A

The chemical that all the genetic material in a cell is made up from. A double stranded polymer of nucluotides, wound to form a double helix.

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2
Q

What are chromosomes and what is their function

A

Coiled up lengths of DNA that determine the characteristics you have

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3
Q

What is the Shape of DNA

A

Double helix

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4
Q

What is a gene

A

A small section of DNA found on a chromosome that codes for a specific sequence of amino acids which undergo polymerisation to form a protein

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5
Q

What does each gene do

A

Code for a particular sequence of amino acids

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6
Q

How many amino acids are there

A

20

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7
Q

What determines what proteins the cells produce

A

DNA

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8
Q

What is a genome

A

The entire genetic material of an organism

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9
Q

Reasons understanding the human genome is important (3)

A

Scientists can identify which genes are linked to different diseases- Knowing which genes are linked to inherited diseases could help us understand them better and how to treat them - Trace immigration

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10
Q

What is sexual reproduction

A

Type of reproduction that involves the production of gametes with meiosis. gametes from each parent fuse to form zygotes

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11
Q

What are gametes

A

Sex cells that are haploids meaning they have half the number of chromosomes

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12
Q

What is meiosis

A

Cell division that forms gametes in reproductive organs, involving the halving of the chromosomes and 2 divisions

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13
Q

What occurs prior to meiosis

A

interphase- copies of genetic information are made during this process

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14
Q

What happens in the first stage of meiosis

A

Chromosome pairs line up at center-Pair of chromosomes separated and move tp opposite poles at random-Membrane splits -Chromosome number halved

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15
Q

What happens in the second stage of meiosis

A

-Chromosomes line up along centre -Chromatids separated and move to opposite poles -Membrane splits again-4 unique haploid gametes are produced

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16
Q

Why is meiosis important for sexual reproduction (2)

A

Increases genetic variation -Ensures zygote formed at fertilisation is diploid

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17
Q

Descrtibe fertilisation and its resulting outcome

A

gametes join together to restore the normal number of chromosomes and the new cell then divides by mitosis -As the embryo develops, cells differentiate

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18
Q

What is asexual reproduction

A

Reproduction that only requires one parent and only involves mitosis

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19
Q

What is a chromosome

A

A long, coiled molecule of DNA that carries genetic information

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20
Q

How many chromosomes do human body cells have

A

46 (23 pairs)

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21
Q

How many chromosomes do human gametes have

A

23

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22
Q

What is a nucleotide

A

A monomer of DNA

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23
Q

What are nucleotides made of

A

Sugar -Phospate -(Nitrogenous) Base

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24
Q

What is a gene

A

Small section of DNA that codes for a specific sequence of amino acids which undergo polymerisation to form a protein

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25
Q

What are monomers of DNA

A

Nucleotides

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26
Q

What are alleles

A

Different versions of the same gene

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27
Q

What is a dominant allele

A

A version of a gene where only one copy is needed for it to be expressed

28
Q

What is a recessive allele

A

a version of a gene where two copies are needed for it to be expressed

29
Q

Wat is meant when an organism is homozygous

A

When an organism has two copies of the same allele (two recessive or two dominant)

30
Q

What is meant when an organism is heterozygous

A

When a organism has two different versions of the same gene (one recessive or one dominant)

31
Q

What is the genotype

A

The alleles present for a particular gene

32
Q

What is a phenotype

A

The visible characteristic

33
Q

How are dominant alleles represented in a punnett square

A

Uppercase letters

34
Q

How are recessive alleles represented in a punnett square

A

lowercase version of same leter as dominant allele

35
Q

Draw a punnet square for a cross between a homozygous recessive blue eyed female (bb) with a heterozygous brown eyed male (Bb)

A

:

36
Q

Draw a punnet square for a cross between a homozygous dominant blue red flower (RR) with a homozygous recessive white flower (rr)

A

:

37
Q

Draw a punnett square for a cross between two heterozygous custic fibrosis carriers (Ff)

A

:

38
Q

PKU is a recessive condition. Two heterozygous parents (Pp) have offspring, predict the proportion of offspring that will have PKU (draw punnets square)

A

75% chance of having normal phenotype and 25% chance of PKU phenotype

39
Q

what is the problem with single gene crosses

A

Most characteristics are controlled by multiple alleles rather than just one

40
Q

What is an inherited disorder

A

A disorder that?s caused by the inheritance of certain alleles

41
Q

2 examples of inherited diseases and what gene they are caused by

A

Cystic fibrosis (caused by a recessive allele), polydactyl (caused by dominant allele)

42
Q

How embryos screened for inherited diseases

A

during IVF, one cell is removed from 8 cell embryo and tested for allele caused disorders. If cellhas no indicator alleles, then embryo is implanted into uterus

43
Q

3 ethical issues with embryo screening

A

Could lead to beliefs of inferiority of disabled people or people with disorders, destruction of embryos with inherited disorders seen as murder by some people, Could be views as part of designer baby concept

44
Q

what is gene therapy

A

Insertion of normal allele into cells of person with inherited disorder to functionally replace the faulty allele

45
Q

Ethical issues of gene therapy (2)

A

Some believe that it is going againt god, Introduced genes could enter sex cells and be passed to future generations

46
Q

What are sex chromosomes and which do males and females have

A

Pair of chromosomes that determine sex: males= XY females=XX

47
Q

economic issue concerning embryo screening

A

Costs of hospital tretment and medicationj will need to be considered if it is known that a child will have an inherited disorder and financial support explored if necessary (insurance)

48
Q

Social positive of embryo screening

A

if embryo terminated, future suffering is prevented

49
Q

what is a species

A

A group of organisms with similar characteristics which are able to interbreed to produce fertile offspring

50
Q

4 different bases

A

A,C,G,T

51
Q

Which bases are complementery

A

A,T and G,C

52
Q

Describe how nucleotides interact to form a molecule of DNA

A
  • Sugar and phosphate molecules join to form a sugar phosphate backbone in each DNA strand
  • Base connected to each sugar
  • Complementary base pairs joined by weak hydrogen bonds
53
Q

How does a gene code for a protein

A
  • A sequence of three bases in a gene forms a triplet
  • Each triplet codes for an amino acid
  • The order of amino acids determines the structure and function of protein formed
54
Q

Why is the folding of amino acids important in proteins

A

It folds into a unique shape that enables the protein to do their job as enzymes, hormones or forming structures like collagen

55
Q

2 stages of proteinj synthesis

A

transcription and translation

56
Q

What happens in transcription

A

The formation of mRNA form a DNA template

57
Q

Outline transcription (4) or simple

A
  1. DNA double helix unwinds
    2.RNA polymerase binds to a specific base sequence of non-coding DNA in front of a gene and moves along the DNA strand
  2. RNA polymerase joins free RNA nucleotides to complementery bases of the coding DNA strand
    4.mRNA formation is complete and the mRNA detatches and leaves the nucleus
    simple:
  3. DNA double helix unwinds
  4. Base sequence of gene is copied into complementary mRNA
    This leaves the nucleus
58
Q

What happens in translation

A

A ribosome joins amino acids in a specific order dictated by mRNA to form a protein

59
Q

Outline translation (4)

A
  1. mRNA attatches to a ribosome
  2. Ribosome reads mRNA bases in triplets.
  3. Each triplet codes for one amino acid, so amino acids brought to the ribosome by a tRNA molecule
  4. ribosome reads triplets of bases on mRNA and causes it to join amino acids in correct order, then it fold into shape
60
Q

What does a base triplet do

A

Code for one amino acid

61
Q

Importance of understanding human genome (3)

A

Search for genes linked to different types of diseases
understanding and treating inherited disorders
tracing human migration patterns from the past

62
Q

What is a mutation

A

A random change in the base sequence of DNA which results mostly in no change to the protein coded for, or genetic variants of protein (slight alteration but appearance and function remain)
Occur continuously

63
Q

Describe the effect of a gene mutation in coding DNA

A
  • If mutation changes the amino acid sequence, protein structure and function may change
  • If mutation does not change amino acid sequence, there is no effect on protein structure/function
64
Q

Effect of gene mutation in coding DNA for enzyme

A

Enzyme shape may change so active site doesn’t fit substrate and structural proteins may lose their strength

65
Q

What is non-coding DNA

A

DNA which doesn’t code for a protein but instead controls gene expresion

66
Q

Effect of gene mutation on non-coding DNA

A

Gene expression may be altered, affecting protein protein and the phenotype

Biology (9 decks)

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