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Biology 1 > Mutation and Genetics > Flashcards

Mutation and Genetics Flashcards

1
Q

What is mutation?

A

A change in the amount or structure of DNA of an organism, resulting in change of genotype.
Can occur in somatic or gamete cells.

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2
Q

What is germ-line mutations?

A

Occurs in gamete or in cells giving rise to gametes.
Occurs by meiosis which changes to genome of gamete.
May be transmitted to offspring and future generations.

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2
Q

What is a mutant?

A

Organism with characteristics changed by mutation.

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3
Q

What is somatic mutations?

A

Occur in somatic cells.
Inherited by daughter cells produced by mitosis.
Affects the cell descended from the mutated cell but not transmitted to next generations.

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4
Q

What are two kinds of mutation?

A

Gene/point mutation
Chromosomal mutation

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5
Q

What is point mutation?

A

Change in base sequence of DNA in a particular region of chromosome.
Change transmitted to mRNA during transcription which results in change of amino acid sequence in polypeptide chain during translation.

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6
Q

What is 4 types of point mutation?

A

Substitution
Inversion
Insertion
Deletion

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7
Q

What are some affects of mutation on mRNA sequence?

A

Silent
Missense
Nonsense
Frameshift

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8
Q

What is silent affect?

A

Point mutation that codes for the same amino acid and no effect on translated protein.

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9
Q

What is missense affect?

A

Base-pair substitution that results in replacement of one amino acid by another.
If occurs at or near active site of an enzyme, activity of altered enzyme may destroyed or decrease. (no more specific shape)
Some changes is not essential to protein’s function.
Changes in closely related amino acid still has no effect on function of gene product and may be undetectable.

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10
Q

What is nonsense affect?

A

Base-pair substitution that convert an amino acid specifying codon to a stop codon.
Destroys the function of gene product and no protein is translated.

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10
Q

Talk about substitution.

A

One nucleotide in gene is replaced by another nucleotide.
Causes silent, missense and nonsense.

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11
Q

What is frameshift affect?

A

Inserted or deleted nucleotide pairs which alters reading frame of nucleotide sequence.
Produces stop codon or altered and new amino acid sequence.
Produces non functional proteins.

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12
Q

Talk about inversion.

A

Nucleotides exchange places and nucleotide sequence.
Causes missense (faulty or non functional protein produced)

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13
Q

Talk about insertion.

A

1 or more nucleotides inserted into polynucleotide chain.
Produce an entirely new sequence of codons at and after point mutation.
Causes frameshift

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14
Q

Talk about deletion.

A

1 or more nucleotides deleted from polynucleotide chain.
Causes frameshift.

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15
Q

What is chromosomal mutation?

A

A change in arrangement or amount of DNA chromosome.
May affect several genes (more severe than point mutation)
Either structural modification or irregular number of homologous chromosome.

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16
Q

Talk about chromosomal number mutation.

A

Changes due to error during meiosis and sometimes mitosis.
Two types: polyploidy and aneuploidy

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17
Q

What is polyploidy?

A

Involves whole set of chromosome in multiple numbers.
Two types: autopolyploid, allopolyploid

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18
Q

Why is polyploidy rare in animals but common in plants?

A

Increase number of chromosomes including sex chromosomes resulting in error during gamete formation.
Plants reproduce vegetatively (grow from other part) and gives advantageous features (size increase, more resistance)

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19
Q

Talk about autopolyploid.

A

More than 2 sets of chromosomes derived from a single species.
Even number chromosomes = fertile
Caused by doubling in somatic cells undergoing mitosis or union of unreduced gametes during meiosis.

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20
Q

Talk about allopolyploid.

A

More than 2 sets of chromosomes derived from different species.
F1 hybrids are sterile (cannot form homologous pair during meiosis) but can become fertile if undergoes somatic doubling during mitosis.
Union of unreduced gametes from different species also produce fertile F1 hybrids.

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21
Q

What is aneuploidy?

A

Organism lose or gain 1 or more individual chromosomes from the 2n total due to non disjunction.

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22
Q

What are the two types of non disjunction?

A

Meiotic and mitotic

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23
Q

Talk about meiotic ND.

A

Results in abnormal chromosome number at zygote stage of development.
All cells will have abnormal chromosome number.

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24
Q

Talk about mitotic ND.

A

Occurs later in development and leads to clone of abnormal cells in normal individual (will have mixture of cells with different chromosome number = cancer cells)

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25
Q

How does meiotic non disjunction occur?

A

Homologous chromosome do not move apart properly during meiosis I (unequal distribution)
Sister chromatids fail to separate during meiosis II.

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26
Q

Talk about non disjunction in sex chromosomes.

A

Can be fatal but mostly not (chromosomes 1-22 are fine)
effects secondary sexual characteristics, fertility and intelligence.
Turner, Klinefelter, Trisomy X

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27
Q

Talk about non disjunction in autosomes.

A

more severe (affects chromosome 1-22)
Down syndrome

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28
Q

What is Turner syndrome?

A

Only one sex chromosome (XO) monosomy X.
Individual develops as female (lack male determining effect of Y chromosome)
No matured sex organs (sterile)
Short, fold of skin around their neck
Normal intelligence
Fail to menstruate and develop secondary sexual characteristics.

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29
Q

What is Klinefelter syndrome?

A

XXY
Have male sex organs with abnormally small testes.
Mixed secondary sexual characteristics at puberty
Sterile, taller than average
Normal intelligence

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30
Q

What is trisomy X?

A

XXX
Healthy and cannot be distinguished from XX females except by karyotype.
No detectable defects but mentally retarded.
Fertile and almost always bear normal children.

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31
Q

What is Down syndrome?

A

Extra autosomal chromosome 21.
Non disjunction of chromosome 21 during meiosis
Mental retardation, less resistance, short and thick neck.

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32
Q

Talk about chromosome structural mutation.

A

Errors in replication or recombination results with breakage of chromosomes.

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33
Q

What are the four structural changes of chromosome?

A

Deletion
Duplication
Translocation
Inversion

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34
Q

What is deletion?

A

Loss of segment of chromosome.
Break and fail to rejoin (missing in certain genes)
Large deletions are lethal while small deletion usually no effect or cause human disorder.

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35
Q

What is an example of disease caused by deletion?

A

Cri-du-chat syndrome
Short arm of chromosome 5 is deleted.
Small head with moon face
Retard, abnormally shaped larynx (cries sound like meow)

36
Q

What is duplication?

A

A segment of chromosome is duplicated (additional set of genes)

37
Q

What is inversion?

A

A segment of chromosome breaks off, rotates 180 and rejoins in chromosome.
Change in phenotype not genotype (position effect)
Hemophilia A (no blood clotting)

38
Q

What is translocation?

A

A segment of chromosome breaks off then rejoins at non homologous chromosome.

39
Q

What is two types of translocation?

A

Reciprocal (non homologous chromosome exchange fragments)
Non reciprocal (a chromosome transfers a fragment but receives nothing in return)

40
Q

What is mutagen?

A

Environmental agents
Usually carcinogens (cancer causing)

41
Q

What are some examples of chemical mutagens?

A

Nicotine
Smoke
Pesticide
Drugs
Pollution

42
Q

What are some examples of physical mutagens?

A

UV rays
Radiation
Extreme heat

43
Q

What are some examples of biological mutagens?

A

Bacteria
Virus

44
Q

What is chemical mutagens capable of?

A

React and modify bases in DNA
Bases inserted or deleted from DNA

45
Q

What is physical mutagens capable of?

A

Break up DNA
Cumulative effects

46
Q

What is genetic technology?

A

Techniques and methods used in understanding gene expression and gene manipulation.

47
Q

How does genetic engineering work?

A

Modify and recombine DNA (rDNA) to produce desirable products (proteins) or animals or plants with desirable traits.

48
Q

What are three types of genetic engineering?

A

Recombinant DNA technology (rDNA)
Gene cloning
Polymerase Chain Reaction (PCR)

49
Q

What is rDNA?

A

Formation of new combination of genes by isolating genes from one organism and introduce them into similar or unrelated organism.

50
Q

What are the tools used in rDNA method?

A

Target DNA (gene of interest)
Restriction enzyme
Vector
Modifying enzyme
Host cell

51
Q

Talk about restriction enzyme.

A

Used to cut DNA into specific fragments.
Known as Restriction Endonuclease.
Degradative enzyme found in bacteria used as defense against bacteriophage.

52
Q

How do bacteria use restriction enzyme against bacteriophage?

A

Bacteriophage (virus that infects bacteria) injects its DNA into bacterial cell.
RE cuts the DNA into smaller fragments
Bacteria cells protects its own DNA by attaching methyl groups to its DNA nucleotide for RE to not recognize and cut it.

53
Q

How does RE cuts DNA?

A

In palindromic sequence
Base sequence of one strand reads the same as its complement when both are read in 5’ to 3’ direction.
Two types : blunt end, sticky end

54
Q

How does sticky ends base pair?

A

Pair with complementary, single stranded ends of other DNA molecules cut by same RE by hydrogen bonding.
Sealed by DNA ligase by covalent bond.

55
Q

What are some examples of RE?

A

EcoR1 (sticky end)
BamHI (sticky end)
HaeIII (blunt end)

56
Q

What is a vector?

A

The genome/DNA molecule that carries the foreign DNA into the host.
Replicates within the host cell to produce clones
Can express the cloned genes in host
Two types: plasmid and bacteriophage

57
Q

Talk about plasmid.

A

Circular DNA molecules
Exist independently in bacterial cell
Uses host RE
Replicate together with their genes each time bacteria divides (copies distributed into daughter cells)
Can be engineered in laboratory for helpful features.

58
Q

What are some helpful features for plasmid?

A

Antibiotic resistance genes (remove bacteria without rDNA)
Origin of replication
Number of restriction sites
Nutrients preference for host cell.

59
Q

What are the three possibilities of bacteria after transformation process?

A

Vector has successfully combined with target gene (inserted into bacteria beside its own DNA)
Vector simply combined with itself (no rDNA)
Bacteria didn’t receive any rDNA

60
Q

What is a host cell?

A

Living cell that can accept rDNA, maintain rDNA in cell after many generations, produce/express cloned genes.
Example: E coli

61
Q

How to produce recombinant DNA?

A

Remove the gene of interest from DNA of donor cell and obtain a copy of the required gene through fragmentation of DNA with restriction enzymes.
Cut the plasmid DNA with the same restriction enzyme.
The restriction fragments from the donor DNA containing the required gene are then mixed with the plasmid DNA by their sticky/blunt ends.
The initial binding is by hydrogen bonding, but then will be sealed by DNA ligase by covalent bonding.
The rDNA will be inserted into a host bacterial cell through transformation process.
Bacteria will replicate this recombinant plasmids independently of their main bacterial chromosome.

62
Q

What is genetic cloning?

A

Process of producing multiple copies of certain genes/DNA fragments.

63
Q

What are the general steps of gene cloning?

A

Isolation of vector and target DNA.
Cutting of both vector and DNA with the same restriction enzymes.
Insertion of target DNA into vector.
Transformation of rDNA into host cell.
Plating and incubating of the host cell.
Identification of cloned cells with the right gene.

64
Q

Talk about the isolation process.

A

The target DNA is grown in lab culture.
Plasmid as vector carries two useful genes with a single recognition sequence (within LacZ gene) for RE used.

65
Q

What are the two useful genes carried by plasmid?

A

ampR = resistance to ampicillin antibiotic
lacZ = encodes the enzyme beta galactosidase which catalyzes sugar hydrolysis.

66
Q

Talk about cutting and joining of target DNA and vector.

A

Both are digested with the same RE.
RE cuts plasmid at its single restriction site within LacZ gene.
All fragments have complementary sticky ends.
Base pairing of sticky ends by hydrogen bonding.
DNA ligase seals the strands by covalent bond and forms rDNA (also forms rejoined, non recombinant version of original plasmid)

67
Q

Talk about transformation.

A

Foreign DNA is introduced into host cell (E coli)
Plasmid transformed into host through heat shock technique. (high temperature encourages bacterial cells to take up rDNA)
Usually placed in water baths.

68
Q

Talk about plating and incubating.

A

Transformed bacteria are plated on a solid nutrient medium (agar) containing antibiotic (ampicillin) and X-gal (growth nutrient).
Only bacteria with antibiotic resistance gene plasmid will grow.
Each reproducing bacteria forms a clone by repeating cell divisions and generate a colony of cells on the agar.

69
Q

What is the purpose of X-gal?

A

Identifies recombinant plasmids.
LacZ gene encodes beta galactosidase enzyme to digest lactose of X-gal into monosaccharide.
As the gene of interest is inserted within LacZ gene, it’s now broken so rDNA will not produce beta galactosidase (white colonies)
For non rDNA, BG is produced and digests the X-gal (blue colonies)

70
Q

Talk about identification.

A

White colonies which contain rDNA are transferred to new agar plate through inoculation.
This allows growth into visible colonies with all cells containing the same rDNA.

71
Q

What are the two ways genes are expressed?

A

As the gene itself or as the protein expressed from gene of interest and harvested.

72
Q

What is polymerase chain reaction?

A

In vitro technique to rapidly replicate or amplify selected DNA segments that are initially present in extremely small amounts.

73
Q

What are the requirements for PCR?

A

Target DNA segment/gene
DNA polymerase (Taq polymerase)
DNA primer
Nucleotides

74
Q

What is Taq polymerase?

A

Enzyme that synthesize new strands of DNA using existing strands as templates.

75
Q

What is DNA primer?

A

Short sequence of single stranded DNA that provides a starting point for DNA synthesis.
Two primers for each PCR reaction where they bind to opposite strands of the template DNA.

75
Q

What is the nucleotides?

A

Building blocks of bases in which the DNA polymerase synthesize a new DNA strand.

75
Q

What are the three main process of PCR?

A

Denaturation (strand separation)
Annealing (primer binding)
Extension (DNA synthesis)

76
Q

Briefly explain about PCR.

A

D = 95C heat separates DNA strands.
A = 53C cool allows primers to form H bonds with ends of target sequence.
E = raised to 73C to enable Taq polymerase add nucleotides to 3’ end of each primer, forming two identical double stranded DNA.
Solution is heated again to start next cycle for DAE.

77
Q

What are the advantages of PCR?

A

Large quantities of target DNA can be replicated.
Amplification of DNA without cells.
Quick
Only need small amount of DNA source.

78
Q

What is a gene library/bank?

A

Collection of bacterial or bacteriophage clones with each containing copies of a particular DNA segment from foreign genome.

79
Q

What are the methods to produce genomic library?

A

Extract and purify human and plasmid DNA.
Cut both with same RE and mixed together.
Add DNA ligase to form rDNA.
Introduce into host cell for transformation.
Each bacteria with different human DNA segment cultured on nutrient agar plate.
Bacteria reproduces forming colonies.

80
Q

What is a transgenic organism?

A

Plants and animals in which foreign genes have been incorporated.
Used in research
Produce genetically modified proteins.
Important in agriculture

81
Q

What is pharming?

A

Producing transgenic livestock that secrete foreign proteins in their milk.
No harm to animals, protein produced in large amounts, offspring carries stain.
Cows contain human gene that codes for lactoferrin (protein in breast milk) and secretes in their milk.

82
Q

What is biotechnology?

A

Commercial or industrial use of cells or organism.
Used in environment, food, medicine, agriculture.

83
Q

What is genetic screening?

A

Application of test on people for the systematic early detection of a hereditary disease or genetic predisposition to disease or determine whether a person carries predisposition which may produce hereditary disease in their offspring.
Test a sample of DNA for mutated sequence. (can be taken from any tissues)

84
Q

What are the types of genetic screening?

A

Predictive and presymptomatic testing
Forensic testing
Newborn testing
Preimplantation testing
Carrier testing
Diagnostic testing

85
Q

What is DNA fingerprinting?

A

Analysis of DNA fragments unique to an individual.
Relies on PCR amplification and gel electrophoresis to detect molecular markers.

86
Q

What are some useful molecular marker?

A

Short tandem repeat (STR) :
Short sequence of repetitive DNA
Up to 200 nucleotide base with simple pattern.

87
Q

What are the applications of DNA fingerprinting?

A

Forensic analysis of crime scene evidence
Identify mass disaster victims
Pedigree verification of dogs
Identify human cancer cell lines
Study endangered species
Track tainted food
Human genetic ancestry
Paternity testing
Exonerate the wrongly convicted.

88
Q

What are some applications in medicine?

A

Gene therapy uses specific DNA to treat genetic disease by correcting the genetic problem.
rDNA is used to produce medical proteins, human insulin or recombinant vaccines.

Biology 1 (10 decks)

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