Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology Module 6 Genetics, Evolution And Ecosystems > Chapter 19 Genetics Of Living Systems > Flashcards

Chapter 19 Genetics Of Living Systems Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a mutation?

A

A change in the amount or the structure of DNA in an organism where the genotype changes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a gene mutation?

A

A change in the nucleotide (base pair) sequence of single genes or small sections of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a chromosome mutation?

A

A change in several genes that can affect portions
of a chromosome or numbers of chromosomes in a cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a gene point mutation?

A

A mutation that happens to one base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What causes mutations in genes?

A

The change in the sequence of bases can be caused by:
Substitution
Deletion
Insertion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is substitution in gene mutation?

A

Changes a base in the codon sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the affect of substitution?

A

If the new codon codes for a different amino acid then this will change the primary structure of the protein.
However, due to the degenerative nature of the genetic code this means that the new codon could still code for the same amino acid and therefore have no effect on the sequence or the protein synthesised.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is insertion in gene mutation?

A

A base is added to the sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is deletion in gene mutation?

A

A base is removed from the sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the affect of insertion and deletion?

A

Insertion and deletion can cause frameshift mutation where the mutation changes the reading frame of the codon. This alters every successive codon from the point of mutation.
This changes the amino acid which is coded for and therefore the protein synthesised.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When does insertion or deletion have no effect on the reading frame of the codon?

A

When the number of bases changed are multiples of three as they correspond to full codons and the reading frame does not shift.
However, the protein synthesised will still be altered as the amino acids have changed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the effects of mutations?

A

-No effect on the phenotype of an organism
-Damaging- the phenotype is affected negatively as proteins are no longer synthesised or proteins are non-functional.
-Beneficial- a different protein structure is synthesised which is advantageous to the phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an example of a neutral mutation?

A

Dimples
Free/ attached ear lobes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an example of a damaging mutation?

A

Cystic fibrosis
Sickle cell anaemia
Colour blindness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an example of a beneficial mutation?

A

Lactose persistence
HIV resistance
Bacterial antibiotic resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are Mutagens?

A

A chemical, physical or biological agent which increases the risk of mutation rates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are causes of mutation?

A

-Mutagens
-The loss of a purine or pyrimidine base during DNA replication can result in the replacement of the incorrect base
-Free radicals can affect the structures of nucleotides and disrupt base pairing during DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is an example of a physical mutagens?

A

Ionising radiation
Can break DNA strands leading to mutations during repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is an example of a Chemical mutagen?

A

Deaminating agents- chemically altering bases in the DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an example of a biological mutagen?

A

-Viruses - viral DNA may insert itself into the genome changing the base sequence
-Base analogs - are incorporated into DNA in place of the usual base during replication
-Alkylating agents - methyl to ethyl groups are attached to bases resulting in the incorrect pairing of bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How are mutations formed in chromosomes?

A

Deletion
Translocation
Inversion
Duplication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is Deletion in chromosome mutation?

A

A section of the chromosome is lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is duplication in chromosome mutation?

A

A section of a chromosome is duplicated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is translocation in chromosome mutation?

A

A section of the chromosome breaks off and joins another non-homologous chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is inversion in chromosome mutation?

A

A section of a chromosome breaks off, is reversed and then joins back onto the chromosome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When does chromosome mutation occur?

A

Meiosis, during crossing over in Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the impacts of chromosome mutations?

A

Addition or loss of chromosomes can lead to gametes with too few or too many chromosomes.
Therefore, this can lead to developmental problems within the zygotes that survive.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is gene regulation?

A

Controls what genes are switched on or off and the rate of synthesis of proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the function of regulatory mechanisms?

A

Control which genes are expressed at different points in time to ensure that the correct gene is expressed in the correct cell at the right time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the different regulatory mechanisms?

A

Transcriptional
Post-transcriptional
Translational
Post -translational

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is gene regulation used for in multicellular organisms?

A

Gene regulation is used by multicellular organisms in order for their cells to specialise and work together in co-ordination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What does the transcriptional mechanism control?

A

Switching genes on or off to control whether transcription occurs or not .

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does the post-transcriptional mechanism control?

A

Modifying mRNA to regulate translation and the types of protein produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What does the translational mechanism control?

A

Stopping or starting translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What does the post-translational mechanism control?

A

Controls the modification of proteins after synthesis which changes their function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are the similarities in the gene expression of eukaryotes and prokaryotes?

A

Both respond to stimuli by changing gene expression
Both change product synthesis rates according to demand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the differences in the gene expression between prokaryotes and eukaryotes?

A

Prokaryotes
Responses produced are simple
Only respond to changes in the external environment

Eukaryotes
Responses produced are complex
Respond to changes in the internal and external environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the structure of a chromatin?

A

DNA is wound around histone proteins forming chromatin.
The DNA is negatively charged and coils around the positively charged histone

39
Q

What is Heterochromatin?

A

Tightly wound DNA which forms chromosomes during cell division

40
Q

What is Euchromatin?

A

Loosely wound DNA present during interphase

41
Q

What are examples of epigenetics?

A

-Adding acetyl groups of phosphate groups to histone proteins
-Adding a methyl group to DNA

42
Q

What is the effect of decondensing chromatin?

A

Activates transcription

43
Q

What is the effect of condensing chromatin?

A

Suppresses transcription.

44
Q

What is a structural gene?

A

A gene that codes for proteins in the body needed for structure and function

45
Q

What is a regulatory gene?

A

A gene that makes transcription factors

46
Q

What are transcriptional factors?

A

Proteins that can bind to the DNA to inhibit or initiate transcription, so only certain parts of the DNA are expressed.

47
Q

How are transcriptional factors able to bind to DNA?

A

The proteins have a unique 3D shape which is complementary to the sequence of bases.

48
Q

Describe how the transcription of target genes are expressed in eukaryotes

A

Target genes can be expressed when specific transcriptional factors move from the cytoplasm into the nucleus where they bind to DNA.
This can either inhibit or initiate genes so only certain proteins are produced
During initiation, RNA polymerase is able to bind, initiating transcription so mRNA is formed for the translation of a particular protein.
During inhibition, RNA polymerase is inhibited from binding preventing transcription.

49
Q

What happens when a transcriptional factor does not bind to DNA?

A

The gene becomes inactive so the protein will not be made

50
Q

What controls transcription in eukaryotes?

A

Transcriptional factors
Epigenetics

51
Q

What controls transcription in prokaryotes?

A

Operons

52
Q

What is a repressor protein?

A

A protein that inhibits the expression of one or more genes

53
Q

What is an operon?

A

A group of structural genes that are under the control of the same regulatory mechanism and are expressed at the same time.

54
Q

What is lac operon?

A

Found in E.coli composed of three genes, lac Z, lac Y and lac A that aid lactose digestion.

55
Q

What are the three genes in lac operon?

A

Lac Z
Lac Y
Lac A

56
Q

What is the function of lac operon?

A

Regulates the transcription of the genes that aid lactose digestion to meet demands, as this is only needed when glucose is short.

57
Q

What is lac L?

A

A regulatory gene found near the operon, which codes for a repressor protein that inhibits transcription when no lactose is present.

58
Q

Describe the process of lac operon gene expression in the absence of lactose

A

When lactose is absent, the repressor protein is constantly produced by the regulatory gene and it binds to the operator region, which prevents RNA polymerase from binding to DNA at the promoter region so transcription is inhibited so only the enzymes used for the respiration of glucose are made.

59
Q

Describe the process of lac operon gene expression in the presence of lactose

A

In the presence of lactose, lactose will bind to the repressor protein causing it to change shape. This change prevents the repressor protein from binding to the operator and therefore RNA polymerase can bind to the promoter region. Transcription of lac operon can then occur so lactase enzymes can be made to respire lactose.

60
Q

How can the rate of transcription for lac operon be increased?

A

The rate of transcription needs to be up-regulated in order to produce the required quantity of enzymes to metabolise lactose efficiently. This is achieved through the binding of the Cyclic AMP receptor protein (CRP), however CRP can only bind and increase the rate of transcription once it has bound to cAMP.

61
Q

What are epigenetics?

A

A heritable (can be passed from cell to cell during cell division) change in gene function without changing the DNA base sequence.

62
Q

What are epigenetics caused by?

A

Changes to the environment which can inhibit transcription

63
Q

What is the Methylation of DNA?

A

A methyl group is added to DNA and attached to a cytosine base. This makes histone proteins more hydrophobic so they bind tightly to each other causing DNA to coil tighter.
Condensing chromatin

64
Q

What happens to transcription when a methyl group is added to DNA?

A

Transcription is inhibited as transcriptional factors are prevented from binding and instead attracts proteins that condense the DNA- histone complex.
This prevents a section of DNA from being transcribed.

65
Q

What happens when acetyl groups are added to Histone proteins?

A

Adding acetyl groups of phosphate groups reduces the histone proteins positive charge so DNA binds loosely. Decondensing chromatin.

66
Q

What happens to transcription when acetyl groups are removed from Histone proteins?

A

The removal of acetyl groups inhibits transcription.
This is because when acetyl groups are removed, the histone become more positive and are attracted more to the phosphate group on DNA.
The DNA and histones therefore become more strongly associated so it is harder for transcription factors to bind.

67
Q

When does Euchromatin occur?

A

Decreased methylation
Increased acetylation of associated histone proteins

68
Q

When does Heterochromatin occur?

A

Increased methylation of DNA
Decreased acetylation of associated histone proteins

69
Q

How does the presence of glucose change the rate of transcription of the lac operon?

A

The presence of glucose prevents the CRP and cAMP from binding resulting in slow transcription.

70
Q

What is pre mRNA?

A

The product of transcription before modification has taken place to produce mature mRNA.
Pre mRNA contains introns and exons.

71
Q

What are introns?

A

Non-coding DNA

72
Q

What are exons?

A

Coding DNA

73
Q

What are the processes within post transcriptional control?

A

Pre mRNA can be modified as a result of:
-RNA processing
-RNA editing

74
Q

Describe how pre mRNA is modified during RNA processing

A

Pre mRNA is modified in the nucleus
-Splicing occurs where the introns are removed and the exons are joined together
-A cap is added to the 5’ end of the mRNA and a poly-A tail (long sequence of adenine bases) is added to the 3’ end.

75
Q

What is the purpose of adding caps and tails to the pre mRNA?

A

Helps to stabilise mRNA and delay degradation within the cytoplasm

76
Q

Describe how mRNA can be modified as a result of RNA editing?

A

The mRNA nucleotide can also be changed as a result of base addition, deletion or substitution
This increases the number of proteins that can be produced from a single mRNA

77
Q

What is translational control?

A

Mechanisms which regulate the process of protein synthesis

78
Q

What are the mechanisms of translational control?

A

Degradation of mRNA- the more resistant the molecule, the longer lasting it will be in the cytoplasm, so more proteins will be synthesised.

Binding of inhibitory proteins to mRNA prevents it binding to ribosomes and the synthesis of proteins

Activation of initiation factors which aid binding of mRNA to ribosomes

79
Q

What are protein kinases?

A

Enzymes which catalyse the addition of phosphate groups to proteins.
The addition of the phosphate group changes the tertiary structure and function of the protein activating it.

80
Q

What is the role of post translational control?

A

Modifying proteins that have already been synthesised.

81
Q

Describe the processes that can occur during post translational control

A

-Non protein molecules can be added- lipid or carbohydrate chains
-modifying amino acids and the formation of bonds
-modification as a result of cAMP
-folding or shortening of proteins

82
Q

What is a body plan?

A

The general structure of an organism

83
Q

What is the homeodomain?

A

Part of a protein that binds to DNA, allowing the protein to act as a transcription factor.
It binds at the start of developmental genes therefore activating or repressing transcription.

84
Q

Describe the process of apoptosis

A

Enzymes break down cell components and DNA
The cell shrinks and breaks into fragments
Phagocytes then engulf and digest the fragments

85
Q

What are Homeobox genes?

A

Sequences of genes which code for proteins (homeodomain) that regulate the expression of other genes that are involved in the formation of the body in the early stages of development as an embryo.
Homeobox genes are highly conserved (change very little)

86
Q

What organisms contain homeobox genes?

A

Plant, animals and fungi have homeobox genes to control the development of their bodies

87
Q

What are Hox genes?

A

Type of homeobox gene found in animals that is responsible for the correct body development and positioning of body parts (body plan)
The order of the Hox genes in the DNA is the order which their effects are expressed on the organism

88
Q

What is the role of mitosis in the development of body forms?

A

Results in an increase in the number of cells, leading to growth

89
Q

What is the role of apoptosis in the development of body forms?

A

Programmed cell death- removes unwanted cells

90
Q

How can the Hox genes that regulate mitosis and apoptosis be impacted?

A

The genes that regulate apoptosis and the cell cycle can be impacted by external (temperature) and internal (hormones and stress) stimuli.
The effect of this is highest during growth and development.

91
Q

Why does the cell cycle need regulating by genes?

A

To ensure that new cells are only made when they are needed for growth and repair, to preserve energy and prevent tumour formation.

92
Q

What is the role of the tumour suppressor gene?

A

Responsible for making proteins that stop the cell cycle from continuing

93
Q

What is the role of proto-oncogenes?

A

Responsible for producing proteins that initiate the cell cycle.

Biology Module 6 Genetics, Evolution And Ecosystems (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions