Bio 5: Cellular Control Flashcards Preview

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Flashcards in Bio 5: Cellular Control Deck (114):
1

Gene

Length of DNA that codes for one or more polypeptides

2

Polypeptide

Polymer consisting of a chain of amino acids residues joined by peptide bonds

3

Protein

Large polypeptide usually 100 or more amino acids. Some proteins consist of one polypeptide chain and some consist of more than one polypeptide chain.

4

Transcription

mRNA is used.
Hydrogen bonds break
Catalysed by RNA polymerase

5

Translation

Assembly of polypeptides at ribosomes. The sequence is dictated by codons on mRNA.

6

Mutation

Change in the amount of, or arrangement of the genetic material in a cell

7

Chromosome mutations

Changes to the structure of chromosomes and/or to their number

8

DNA mutation

Changes to the genes due to changes in nucleotide base sequences

9

Point mutation/substitutions

One base pair replaces another

10

Insertion/deletion (frameshift)

One or more nucleotide pairs are inserted or deleted from a length of DNA

11

Huntington disease

Expanded triple nucleotide repeat
Normal gene for Huntington protein - repeating CAG

Symptoms include dementia, loss of motor control

12

Sickle cell anaemia

Point mutation on triplet 6 of the beta chains for haemoglobin.

13

Cystic Fibrosis

Deletion of tripled base pairs, deleting an amino acid in the normal polypeptide

14

Allele

An alternative version of a gene. At the same locus on the chromosome and codes for the same polypeptide but the change can alter the proteins structure.

15

Silent mutation

The base triplet has changed but it still codes for the same amino acid, the protein is unchanged

16

Operon

A length of DNA made up of structural genes and control sites.

17

Structural genes

Codes for beta-galactosidase and lactose permease
Each has base pairs that can be transcribed into a length of mRNA

18

Control sites

Operator region: switches on and off structural genes

Promoter region: RNA polymerase binds to it to begin the transcription of the the structural genes

19

Homeobox genes

Controls the development of the body plan of an organism, including polarity and positioning of the organs

20

Apoptosis

Programmed cell death

Enzymes break down cytoskeleton
Cytoplasm is dense
Membrane can changes to blebs
Chromatin condenses
Nuclear envelope breaks
Breaks into vesicles
Taken up by phagocytosis

21

Meiosis

Reduction division
Four daughter cells
Half the number of chromosomes
They are haploid

22

Bivalent

Pair of joined homologous chromosomes

23

Chiasmata

The points where non-sister chromatids within a bivalent join, where they cross over

24

Locus

Position of a gene on a chromosome

25

Crossing over

Prophase I
Non sister chromatids wrap and join at Chiasmata
Chromosomes break here
They rejoin their non sister chromatid in the same bivalent

26

Reassortment of chromosomes

Consequence of random distribution of maternal and paternal chromosomes at the equator

Each gamete is a different mixture of maternal and paternal

27

Reassortment of chromatids

Alignment at metaphase II determines their segregation at anaphase II

(After crossing over they are no longer identical)

28

Fertilisation

One ovum and 300 million spermatozoa

All genetically different

29

Genotype

The allele present within cells of an individual for a particular trait or characteristic

30

Autos ones

Chromosomes not concerned with determining sex

31

Homozygous

Two identical alleles for a gene

32

Heterozygous

Two different alleles of the same gene

33

Phenotype

Observed characteristics in an organism

34

Dominant

An allele is dominant if it is always expressed in the phenotype

35

Recessive

It is recessive if it is only expressed in the phenotype in the presence of another identical allele, or in the absence of a dominant allele

36

Codominant

Two alleles of the same genes are described as Codominant if they are both expressed in the phenotype of a heterozygote

37

Linkage

Two or more genes that are located on the same chromosome
They are normally inherited together because they don't separate in meiosis

38

Sex linkage

A characteristic is sex linked if the genes that codes for it is in the sex chromosomes

39

Haemophilia A

Clotting factors
- factor VIII coded by a gene on X chromosome
Recessive allele expresses an altered protein
Increase in clotting time

Females with the recessive allele - carriers
Males with the recessive allele - haemophilic

40

Duchenne muscular dystrophy

DMD gene for muscle protein dystrophin is on the X chromosome
Boys often get muscle weakness in early childhood
Wheelchair by 10
Death due to complications by 20s

41

Sickle cell anaemia

Beta haemoglobin differ by one amino acid
When this haemoglobin is deoxygenated it becomes deformed and inflexible
After many cycles they becomes unusable

42

Epistasis

The interaction of different gene loci so that one gene locus masks or suppresses the expression of another gene locus

43

Antagonistic recessive Epistasis

The presence of a homozygous recessive gene at one locus prevents the second from being expressed even if the second is dominant.

The alleles at the first locus are described as Epistasic and those at the second are described as hypostatic

9:3:4 ratio

44

Antagonistic dominant Epistasis

The dominant allele at one locus prevents the expression of the gene at the second locus. The presence of one dominant allele at the first locus will mask the expression at the second even if the at the second there is homozygous dominant alleles.

12:3:1 or 13:3

45

Complementary Epistasis

Two genes at different loci need to be present in order to cause a particular phenotype.

Example:
C-R- = purple

46

Chi squared

Statistical test to find out if the difference between observed data and expected data is small enough to be due to chance

47

Discontinuous variation

Clear categories
Qualitative differences
Different alleles at a single locus have large effects on locus
Different gene loci have different effects on the phenotype

48

Continuous variation

Quantitative differences
Traits that have continuous variation are controlled by two or more traits

49

Population

A group of individuals of the same species that can interbred

50

The Hardy Weinberg principle

To calculate allele frequencies

Assumes:
Population is large
Mating random
No selective advantage for any genotype
No mutation, migration or genetic drift

51

Selection pressure

An environmental factor that confers greater chances of survival to reproductive age on some members of the population

52

Stabilising selection

A type of natural selection in which allele and genotype frequency within populations stays the same because the organisms are already well adapted to their environment

53

Genetic drift

The change in allele frequency in a population as some alleles pass to the next generation and some disappear. This causes some phenotypic traits to become rarer or more common

54

Biological species concept

A group of similar organisms that can interbred and produce fertile offspring

55

Phylogenetic species concept

A group of organisms that has similar shape, biochemistry, stages of development and behaviour. They also occupy the same ecological niche.

56

Monophyletic group

One that includes an ancestral organism and all its descendants

57

Paraphyletic group

Includes the most recent ancestor but not all its descendants.

Reptiles is Paraphyletic as it exclude birds which are descendants of reptiles

58

Natural selection

The organisms that are best adapted to their environment are more likely to survive. The favourable alleles are passed to their offspring.

59

Artificial selection

Where humans select the animals with the desirable characteristics. They allows these animals to breed so therefore the offspring have the characteristics wanted.

In cows:
Milk yield measured
Progeny of bulls tested to see which have high milk yield daughters
Artificial insemination
Hormones to make many eggs
Invitro fertilisation
Surrogates

60

Translation

Assembly of polypeptides at ribosomes. The sequence is dictated by codons on mRNA.

61

Mutation

Change in the amount of, or arrangement of the genetic material in a cell

62

Chromosome mutations

Changes to the structure of chromosomes and/or to their number

63

DNA mutation

Changes to the genes due to changes in nucleotide base sequences

64

Point mutation/substitutions

One base pair replaces another

65

Insertion/deletion (frameshift)

One or more nucleotide pairs are inserted or deleted from a length of DNA

66

Huntington disease

Expanded triple nucleotide repeat
Normal gene for Huntington protein - repeating CAG

Symptoms include dementia, loss of motor control

67

Sickle cell anaemia

Point mutation on triplet 6 of the beta chains for haemoglobin.

68

Cystic Fibrosis

Deletion of tripled base pairs, deleting an amino acid in the normal polypeptide

69

Allele

An alternative version of a gene. At the same locus on the chromosome and codes for the same polypeptide but the change can alter the proteins structure.

70

Silent mutation

The base triplet has changed but it still codes for the same amino acid, the protein is unchanged

71

Operon

A length of DNA made up of structural genes and control sites.

72

Structural genes

Codes for beta-galactosidase and lactose permease
Each has base pairs that can be transcribed into a length of mRNA

73

Control sites

Operator region: switches on and off structural genes

Promoter region: RNA polymerase binds to it to begin the transcription of the the structural genes

74

Homeobox genes

Controls the development of the body plan of an organism, including polarity and positioning of the organs

75

Apoptosis

Programmed cell death

Enzymes break down cytoskeleton
Cytoplasm is dense
Membrane can changes to blebs
Chromatin condenses
Nuclear envelope breaks
Breaks into vesicles
Taken up by phagocytosis

76

Meiosis

Reduction division
Four daughter cells
Half the number of chromosomes
They are haploid

77

Bivalent

Pair of joined homologous chromosomes

78

Chiasmata

The points where non-sister chromatids within a bivalent join, where they cross over

79

Locus

Position of a gene on a chromosome

80

Crossing over

Prophase I
Non sister chromatids wrap and join at Chiasmata
Chromosomes break here
They rejoin their non sister chromatid in the same bivalent

81

Reassortment of chromosomes

Consequence of random distribution of maternal and paternal chromosomes at the equator

Each gamete is a different mixture of maternal and paternal

82

Reassortment of chromatids

Alignment at metaphase II determines their segregation at anaphase II

(After crossing over they are no longer identical)

83

Fertilisation

One ovum and 300 million spermatozoa

All genetically different

84

Genotype

The allele present within cells of an individual for a particular trait or characteristic

85

Autos ones

Chromosomes not concerned with determining sex

86

Homozygous

Two identical alleles for a gene

87

Heterozygous

Two different alleles of the same gene

88

Phenotype

Observed characteristics in an organism

89

Dominant

An allele is dominant if it is always expressed in the phenotype

90

Recessive

It is recessive if it is only expressed in the phenotype in the presence of another identical allele, or in the absence of a dominant allele

91

Codominant

Two alleles of the same genes are described as Codominant if they are both expressed in the phenotype of a heterozygote

92

Linkage

Two or more genes that are located on the same chromosome
They are normally inherited together because they don't separate in meiosis

93

Sex linkage

A characteristic is sex linked if the genes that codes for it is in the sex chromosomes

94

Haemophilia A

Clotting factors
- factor VIII coded by a gene on X chromosome
Recessive allele expresses an altered protein
Increase in clotting time

Females with the recessive allele - carriers
Males with the recessive allele - haemophilic

95

Duchenne muscular dystrophy

DMD gene for muscle protein dystrophin is on the X chromosome
Boys often get muscle weakness in early childhood
Wheelchair by 10
Death due to complications by 20s

96

Sickle cell anaemia

Beta haemoglobin differ by one amino acid
When this haemoglobin is deoxygenated it becomes deformed and inflexible
After many cycles they becomes unusable

97

Epistasis

The interaction of different gene loci so that one gene locus masks or suppresses the expression of another gene locus

98

Antagonistic recessive Epistasis

The presence of a homozygous recessive gene at one locus prevents the second from being expressed even if the second is dominant.

The alleles at the first locus are described as Epistasic and those at the second are described as hypostatic

9:3:4 ratio

99

Antagonistic dominant Epistasis

The dominant allele at one locus prevents the expression of the gene at the second locus. The presence of one dominant allele at the first locus will mask the expression at the second even if the at the second there is homozygous dominant alleles.

12:3:1 or 13:3

100

Complementary Epistasis

Two genes at different loci need to be present in order to cause a particular phenotype.

Example:
C-R- = purple

101

Chi squared

Statistical test to find out if the difference between observed data and expected data is small enough to be due to chance

102

Discontinuous variation

Clear categories
Qualitative differences
Different alleles at a single locus have large effects on locus
Different gene loci have different effects on the phenotype

103

Continuous variation

Quantitative differences
Traits that have continuous variation are controlled by two or more traits

104

Population

A group of individuals of the same species that can interbred

105

The Hardy Weinberg principle

To calculate allele frequencies

Assumes:
Population is large
Mating random
No selective advantage for any genotype
No mutation, migration or genetic drift

106

Selection pressure

An environmental factor that confers greater chances of survival to reproductive age on some members of the population

107

Stabilising selection

A type of natural selection in which allele and genotype frequency within populations stays the same because the organisms are already well adapted to their environment

108

Genetic drift

The change in allele frequency in a population as some alleles pass to the next generation and some disappear. This causes some phenotypic traits to become rarer or more common

109

Biological species concept

A group of similar organisms that can interbred and produce fertile offspring

110

Phylogenetic species concept

A group of organisms that has similar shape, biochemistry, stages of development and behaviour. They also occupy the same ecological niche.

111

Monophyletic group

One that includes an ancestral organism and all its descendants

112

Paraphyletic group

Includes the most recent ancestor but not all its descendants.

Reptiles is Paraphyletic as it exclude birds which are descendants of reptiles

113

Natural selection

The organisms that are best adapted to their environment are more likely to survive. The favourable alleles are passed to their offspring.

114

Artificial selection

Where humans select the animals with the desirable characteristics. They allows these animals to breed so therefore the offspring have the characteristics wanted.

In cows:
Milk yield measured
Progeny of bulls tested to see which have high milk yield daughters
Artificial insemination
Hormones to make many eggs
Invitro fertilisation
Surrogates