Molecular Genetics Flashcards
1
Q
Where did nucleic acids get their name?
A
They are weak acidic material that is isolated from the nucleus.
2
Q
What are two types of nucleic acid?
A
DNA= deoxyribonucleic acid and RNA=ribonucleic acid
2
Q
What was the Griffith experiment?
A
Mouse studies
3
Q
What did Griffith find out regarding hereditary information?
A
Hereditary information is passed down from dead bacterial cells to live bacterial cells which turn the live cells from harmless into a disease causing form.
4
Q
What did Rosalind Franklin picture with her experiment?
A
She experimented with x-ray crystallography to study the structure of DNA.
4
Q
What was Avery, Macleod and McCarthy’s experiment?
A
They refined Griffith’s experiment to show that DNA and not proteins were the hereditary material in bacteria.
4
Q
What was the Hershey/Chase experiment?
A
Experimented with a bacteriophage (a virus that infects bacteria) on bacteria to find that DNA and not protein is the transferred hereditary information. They used radioactive taggers.
5
Q
What three things did Linus Pauling propose?
A
- The secondary structure of proteins is an alpha helix shape.
- The DNA is a helix structure.
- The DNA is a triple helix.
6
Q
What did Watson and Crick figure out with Franklin’s picture?
A
They figured out the double helix structure of DNA.
7
Q
What is Meselson and Stahl’s experiment? What did they discover?
A
They discovered the semi-conservative nature of DNA by using isotope nitrogen 15 on the original DNA of bacteria culture. As the bacteria reproduced, the glow of the nitrogen-15 dimmed.
7
Q
Who was the first to make a model of DNA?
A
Watson and Crick
8
Q
Where is DNA found in plants? (3)
A
Nucleus, mitochondria, and chloroplast.
8
Q
Where is DNA found in humans? (2) Which parent passes down each DNA?
A
Nucleus and Mitochondria. Nuclear DNA is passed down by both parents. Mitochondrial DNA is passed down by the mother only.
9
Q
What is the backbone of a DNA molecule made of?
A
Sugar and phosphate.
10
Q
What does a nucleotide consist of?
A
One set of sugar, base, phosphate.
10
Q
What are attached to the sugars in DNA?
A
Nitrogenous bases.
11
Q
What type of bonds connect the nucleotide?
A
Covalent bonds.
12
Q
How many carbons compose the sugar molecules in a DNA molecule?
A
5 carbon sugars
12
Q
What type of bond connects the nitrogenous bases of different strands of DNA?
A
Hydrogen bonds.
13
Q
Name two types of bases and describe each one.
A
Purines are double ring structures. (A and G). Pyrimidines are single ring structures (T and C).
14
Q
What ae the two complementary base pairs?
A
Adenine with Thymine. Guanine with cytosine.
15
Q
What did Chargoff find?
A
He found that A and T and G and C bases are found in equal amount.
15
Q
Draw a nucleotide and a DNA molecule.
A
16
Q
Whose experiment showed that bases are on the inside of DNA and sugars and phosphates are on the outside?
A
Franklin’s Experiment
17
What do you call the fact that DNA strands compliment each other?
Antiparallel
18
What are the two prime ends to strands of DNA?
A 5 prime strand and a 3 prime strand.
18
What is the sugar in DNA called? RNA?
Deoxyribose. Ribose.
19
What nitrogenous base is replaced in RNA? With what?
Uracil (U) replaces thymine (T).
20
What are the three types of RNA? What do they stand for?
mRNA = messenger RNA. tRNA = transfer RNA. rRNA = ribosomal RNA
21
How many strands is RNA?
One
21
What is a structural gene?
A section of DNA that is on a chromosome and encodes for one or more proteins.
21
What is a gene?
A heritable factor that consists of a length of DNA and influences a specific characteristic.
22
What type of DNA do prokaryotes have?
Circular DNA
23
What is the human genome project?
The entire base sequence of human genes.
24
How do alleles differ from each other DNA wise?
They only differ by one or a few bases.
25
How are new alleles formed?
By mutation.
25
What is DNA wrapped around?
Histone which is a protein.
25
What is DNA wrapped around histones called?
Nucleosomes.
26
What do nucleosomes coil into? What happens after that?
Chromatin Fibre. Further condensation of chromatin happens.
27
What does a chromatin form?
A chromosome.
28
What is the difference between a chromatin and a chromatid?
A chromatin forms DNA while a chromatid is one strand of chromosome.
29
What is the Cairn's technique for? How does it work?
The Cairn's technique is for determining the length of DNA. Cells are grown in radioactive thymine. The cells are lysed to isolate the chromosomes. The chromosomes are placed on a photographic surface and rinsed with radioactive sensitive silver bromide emulsion. The silver ions stick to the radioactive thymine and this appears black when film is developed.
30
What has to happen to DNA in order for cells to divide?
DNA must replicate
31
Wat are helicases? Where do helicases bind? What is its purpose?
Helicases are enzymes that bind to DNA at the replication origin and break the H-bonds between the two DNA strands in order to unravel the segment.
31
What is the specific part of the DNA sequence where replication starts called? How many per strand?
Replicon. Can have many per strand.
31
What is a replication bubble? What is a replication fork?
A replication bubble is an unwound open area of a bubble. A replication fork is the y-shaped area at each end of a replication bubble.
31
What does semiconservative mean in regard to DNA?
Each replicated strand of DNA contains one original strand (parent strand) and one new strand (daughter strand).
31
What must cells have in order to replicate DNA? Where does that come from?
Nucleotides which come from the food we eat.
32
What are single strands in a bubble used as?
A template for new DNA.
33
Does replication take place at one location at a time?
No, it takes place at several locations at one time.
34
What binds to DNA to keep the two strands separate?
Proteins
35
What is the starting point for DNA Polymerase III to add its nucleotides called?
An RNA primer.
35
What adds complementary nucleotides in the 5' to 3' direction?
DNA Polymerase III
35
What is elongation?
The process of creating a new strand of DNA.
36
What are the leading vs lagging strand? How are each synthesized?
The leading strand is the one going from 5' to 3' and it is synthesized continuously. The lagging strand is the one going from 3' to 5' and it is synthesized in short fragments called okazaki fragments.
37
Which direction does DNA polymerase III work in?
5' to 3' direction
38
What splices okazaki fragments together after DNA replication is complete?
DNA ligase
39
What enzyme creates the RNA primer?
Primase which is a type of RNA polymerase.
39
Is the overall direction of elongation the same on both the leading strand and the lagging strand? What about the direction of the fork?
Yes. The leading strand follows the direction of the replication fork while the lagging strand goes in the opposite direction.
39
What encodes for the RNA primer? Why is the primer necessary?
Complementary bases to the strand of DNA encoded for the RNA primer. It is necessary since nucleotides can only be added to other nucleotides.
40
What removes the RNA primer once elongation starts?
DNA polymerase I
41
What proofreads DNA to ensure that H-bonds are taking place and bases are placed correctly? It also has the power to excise incorrect bases and replace them with the correct one.
DNA polymerase II
42
What takes place in the termination step of DNA replication?
Completion of new strands and dismantling of replication machine.
43
What are the three steps of DNA replication?
Initiation, Elongation, Termination
44
How many structural genes make up a tertiary structure protein? How about a quaternary structure?
One for tertiary. More than one for quaternary.
44
What does DNA include?
Genes and regions of non-coding DNA.
44
What is a genetic code?
Order of base pairs in a strand of DNA.
45
What is a non-coding DNA?
DNA that does not code for proteins.
46
What does every group of three bases code for in genes?
A specific amino acid or a stop codon.
47
What will the order of the amino acid dictate for the protein?
Its function.
47
What is gene expression?
The process of making a protein from DNA.
47
Where is the information from DNA copied to?
mRNA
48
What is the process of making mRNA from DNA called?
Transcription.
49
What is the process of creating protein in ribosomes from mRNA called?
Translation
50
What is a group of 3 bases called?
Codon
50
If DNA can't leave the nucleus but protein synthesis occurs in cytoplasm, what is the intermediate link? What is this phenomenon called?
mRNA. Called the central dogma.
50
What is a major component of ribosomes?
rRNA
50
What attached to amino acids to match specific amino acids with their code?
tRNA
51
Is genetic code universal? Why or why not?
It is universal because all organisms use the same 4 letter nitrogenous bases.
52
What is the amino acid named methionine?
It is coded for by the start codon that all proteins start will.
52
Can more than one codon encode for the same amino acid? What does this allow for?
Yes. This allows for mistakes to take place without physical errors to the organism.
52
What is the universality of genetic codes good for?
You can use bacterial genome to make human proteins like insulin. This is genetic engineering.
53
What is the sense strand? Antisense strand?
The sense strand is the strand thatcontains the gene that is being used as a template for mRNA. The antisense strand is the complement strand to the sense strand.
53
What do the last three bases code (the last codon) for?
It is a stop codon so it does not code for anything. Only tells the protein synthesis to stop.
53
What is transcription?
The process of making mRNA.
54
What is the sequence on the DNA called that tells RNA polymerase II where to bind?
A promoter.
54
What is RNA polymerase II?
The main enzyme that completes the strand of mRNA complementary to the DNA.
55
What direction does RNA polymerase II work in? What nucleotide does it add instead of thymine.
The 5' to the 3' direction. It adds the nucleotide uracil.
55
The tRNA is attached to an amino acid and what else?
An anticodon.
56
What is translation?
When codons on mRNA are translated into a sequence of amino acids.
56
Where does mRNA move from the nucleus to?
Ribosomes (free floating or on RER)
57
What brings in enzymes to form bons between amino acids?
Ribosomes.
58
What is the difference between the proteins synthesized on free ribosomes vs the ribosomes on RER?
The RER synthesizes proteins for excretion while the proteins made by free ribosomes for are use in the cell.
59
How many codons on mRNA are exposed at a time on the ribosome?
Two codons.
60
What are the three steps of protein formation?
Initiation, elongation, termination.
60
What happens during protein synthesis termination?
The ribosome complex disassembles.
61
What type of bonds bring amino acids together?
Peptide bonds.
62
How many amino acids does one tRNA carry?
One at a time but it goes for multiple trips.
62
Is a mutation a temporary or permanent change in genetic material of an organism?
Permanent
62
What are two types of mutations? Which type is passed on from one generation to the next?
Somatic cell mutations and germ-line mutations. Germ-line mutations are passed on from one generation to the next.
63
What are three areas where mutations can occur? Who is affected?
Germinal mutation = no affect on the carrier but offspring affected, somatic mutation = no affect on offspring but carrier affected, and embryonic mutation = can result in germinal or somatic mutations
64
What is a point mutation?
A mutation where substitution of one nucleotide for another or insertion/deletion of nucleotides.
64
What are two types of mutations? Which is more lethal?
Chromosomal mutations and point mutations. Chromosomal mutations are more lethal.
64
What are two types of point mutations? Which is more lethal?
Base substitution mutations and frame shift mutations (result of addition and deletion of an amino acid). A frameshift mutation is more lethal as completely new proteins are formed.
64
What is a chromosomal mutation?
Rearrangement of genes usually by crossover or by loss/duplication of portions of chromosomes.
65
What type of mutation is non disjunction?
Chromosomal mutation.
66
What is an example of a base substitution mutation? What type of base substitution is it?
Sickle cell anemia where amino acid glutamic acid is replaced with valine. It is a missense mutation.
66
What are the three types of substitution mutations? Explain.
Missense mutation = results in an altered protein. Silent mutation = has no effect since the same amino acid is produced just using a different code. Nonsense mutation = renders gene since it causes a premature stop so protein has no function.
67
Why are nonsense mutations more serious than missense?
A substitution that changes the stop codon will be much more serious. (Same goes with start codons)
67
Which type of variation can actually be beneficial and lead to genetic variation?
Missense mutations.
68
What are two type of causes of mutations?
Spontaneous or induced by a mutagen
69
How do spontaneous mutations occur?
DNA polymerase incorrectly pairs nucleotides.
70
What are three types of mutations caused by mutagens? How do they affect DNA?
Radiation= tears DNA , chemical = mimics part of DNA and infectious.
70
What are most cancers a result of?
A combination of mutations.
71
Do mitochondrial DNA have the same nitrogenous bases as genomic DNA? What is the difference?
They do have the same bases. The number of tRNA and rRNA differs.
72
What can analyzing mitochondrial DNA (mtDNA) be beneficial for?
Tracing lineages
73
What are four examples of genetic engineering?
Cloning, recombinant DNA, gene therapy, DNA fingerprinting
73
What is recombinant DNA?
a molecule of DNA that includes genetic material from different sources
74
What is the basis behind genetic engineering?
Recombinant DNA
74
What are vectors in recombinant DNA? Name some examples.
They provide a means to get genes where you want them. Examples include viruses, bacteria, and plasmids.
75
How do vectors in recombinant DNA replicate? What shape are they?
Self replicating and circular.
75
What are restriction endonucleases? What is the sequence that is cut called?
Restriction enzymes that cut somewhere in the DNA strand that is not at the ends. It is called a target sequence.
76
What is a restriction site?
The part where restriction enzymes cut.
77
What does ligase do for recombinant DNA? What type of endsdo they work with?
Used to rejoin sticky ends of DNA cut with restriction enzymes.
77
What are sticky ends?
When a restriction endonuclease leave staggered ends. Leave a few unpaired bases. This is better for recombination.
77
Name the steps of the recombinant DNA technique.
Use a restriction enzyme to cut a piece of DNA. Use the same enzyme to cut vector DNA. Insert the DNA into the vector. Ligase will join the pieces together. Have hope the cell takes up the DNA. If so, the vector will replicate, transcribe and translate. Use a selection technique to ensure the vector took up the DNA properly.
78
What are five uses for recombinant DNA?
Insert human genes in vectors to get a human trait. Gene therapy. Fight a disease. Selective breeding. Biological warfare.
79
What is gene therapy?
When you provide "fixed" genes to people with faulty genes.
80
What reaction does DNA fingerprinting use?
A polymerase chain reaction.
81
What is the purpose of a polymerase chain reaction?
To create many copies of a fragment of DNA. This allows for multiple testing of the same strand of DNA.
81
What is cut DNA seperated by in DNA fingerprinting?
gel electrophoresis.
82
What is the PCR process in DNA fingerprinting? (5 steps)
1. Heat DNA to denature it.
2. Expose it to a heat resistant polymerase, primers, DNA nucleotides
3. Polymerase copies the DNA
4. Allow to cool so DNA reanneals and reforms
5. Repeat cycle many times.
83
After the PCR process in DNA fingerprinting, what follows?
A restriction enzyme is used to cleave DNA at target sequences.
84
How are different lengths of DNA obtained in DNA fingerprinting?
A restriction enzyme will leave at an exact pattern but patterns exist at different locations in different DNA sequences.
85
Is DNA slightly posItive or negative?
Negative.
86
What is a different name for heat resistant polymerase used for DNA fingerprinting?
TAQ polymerase.
86
What happens in gel electrophoresis?
1. Wells are cut into the gel and DNA is placed in the wells.
2. Electricity is applied to the gel to pull DNA pieces. DNA is negative so will be pulled to the positive charge.
86
Do shorter or longer fragments of DNA move fastest and furthest in gel electrophoresis?
Shorter fragments.
87
How can DNA fingerprinting be used to determine parents?
Certain DNA sequences (fragment lengths) are passed on by either one of the parents and these will show up as bands.
