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Grade 12 bio > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

One gene one enzyme hypothesis

A

Beadle and Tatum. Each gene is unique and codes for the synthesis of a single enzyme.

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2
Q

Why was the one gene one enzyme hypothesis incorrect

A

many proteins are not enzymes and consist of more than one subunit called a polypeptide

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3
Q

One gene- one polypeptide hypothesis

A

Each gene is unique and codes for the synthesis of a single polypeptide.

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4
Q

Central dogma

A

Information flows from DNA to RNA to proteins

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5
Q

Transcription

A

Information coded in the nucleic acids of DNA is copied into the nucleic acids of RNA

First step of protein synthesis

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6
Q

Initiation- Transcription

A

RNA polymerase binds to the DNA and unwinds it near the begging of a gene at a promoter (nucleotide sequence that lies just before a gene and allows for the binding of RNA polymerase)

The TATA box is a region of the promoter that enables the binding of RNA polymerase, prokaryotes have a TATAAT sequence for the same purpose

AT have 2 hydrogen bonds whereas GC have 3

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7
Q

Elongation

A

Coding strand: The DNA strand that is not being copied but contains the same sequence as the new RNA molecule

The new RNA strand elongates as new nucleotides are added 1 by 1and a RNA DNA double helix is formed

Once this unwinds, the DNA double helix reforms

If there is room at the promoter, another strand of RNA will begin to form

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8
Q

Termination- Transcription

A

Happens when RNA recognizes a termination sequence (a sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing)

In prokaryotes, one mechanism involves a protein binding to the mRNA and stopping transcription, another involves the RNA forming a loop and binding with itself.

In eukaryotes, one termination sequence is a string of adenines which are transcribed as a string of uracil’s on the RNA

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9
Q

4) Post- transcriptional modifications

A

Pre-mRNA must undergo additional transformations before it exits the nucleus and enter the ribosome

The poly(A) tail is a chain of adenine nucleotides that are added to the 3’ end of the pre-mRNA molecule to protect it from enzymes in the cytosol

Capping and tailing is when a 5’ cap is added. This is a sequence of 7 G’s that care added to the start of a pre-mRNA molecule, ribosomes recognize this site and use it as the initial site of attachment

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10
Q

Introns

A

non- coding sequences of DNA and they need to be removed. If they were left in, they would alter the sequence of the amino acids that are used to build the protein. It would not fold correctly and therefore would not function correctly

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11
Q

mRNA splicing

A

splicing removes the introns. This occurs at the spliceosome, an enzyme protein complex formed between the mRNA and the snRNPs

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12
Q

Small ribonucleic proteins

A

proteins are proteins that bind to introns and signals them for removal

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13
Q

Alternative splicing

A

is a process that produces different mRNAs from pre-mRNA, allowing more than one possible polypeptide to be made from a single gene. Helps to explain why humans with 20 000 genes can make about 100 000 proteins.

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14
Q

Spontaneous mutations

A

Caused by an error in DNA replication

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15
Q

Induced mutation

A

Caused by the effect of an environmental agent

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16
Q

Mutagen

A

An environmental agent that directly alters the DNA within a cell

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17
Q

Radiation

A

can create/ break bonds which also results in mutations

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18
Q

Mutations

A

Changes in the DNA sequence

90% of our DNA is non coding so we don’t notice most mutation, mutations are much more likely to be noticed in prokaryotes

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19
Q

Small scale mutations (point mutations)

A

A change in a single nucleotide within a gene (substitution, inversion, insertion, deletion)

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20
Q

missense mutation

A

changes a single amino acid in the coding sequence

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21
Q

nonsense mutation

A

results in a premature stop codon

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22
Q

silent mutation

A

does not alter the resulting sequence of amino acids

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23
Q

frameshift mutation

A

shift in the reading frame resulting in multiple missense and/or nonsense effects

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24
Q

Large scale mutations (chromosome mutations)

A

Can involve multiple nucleotides, entire genes or whole regions of chromosomes

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25
Translocation
is the movement of entire genes or sequences of DNA from one chromosome to another. Usually occurs when pieces of chromosomes break off and switch places
26
Transposable elements
move freely around the genome and if they are near a gene sequence they may alter it
27
Inversion
when a portion of a DNA molecule reverses its direction
28
Trinucleotides
can sometimes become unstable and expand uncontrollably (CAG CAG CAG CAG). Results in hunting’s desiese
29
Amplification
gene duplication. Gene/ group of genes is copied to multiple regions of the chromosome
30
Stop codon
UAA, UAG and UGA. Signals the end of a polypeptide chain and causes the ribosome to terminate translation.
31
Translation
Nucleic acid to polypeptide Ribosome moves along the mRNA, the amino acids coded by the mRNA are joined together, one by one, to form the polypeptide encoded by the gene Multiple ribosomes along the same mRNA can simultaneously translate the mRNA and make multiple copies of the protein
32
Initiating translation
Step 1: methionine tRNA forms a complex with the small ribosomal unit. Step 2: This binds to the mRNA at the 5’ cap and then it moves along the mRNA (a process called scanning) until it reaches the first start codon Step 3: The large ribosomal subunit binds, completing imitation
33
Reading frame
A particular system for separating a base pair sequence into readable codons
34
Elongation of the polypeptide chain
tRNAs deliver amino acids from the cytoplasm One arm of the t RNA (anti codon) recognizes the codon of the mRNA Opposite arm carries the corresponding amino acid
35
Termination of protein synthesis
Happens when the A site of a ribosome arrives at one of the stop codons on the mRNA. When this happens, a protein release factor binds at this site instead of tRNA
36
Polysome
A complex that is formed when multiple ribosomes attach to the same mRNA molecule in order to facilitate rapid translation
37
Messenger RNA
is translated into proteins by ribosomes and it’s the RNA version of the gene encoded by DNA
38
Transfer RNA
Very short All of them have regions that base pair with themselves, winding into four double helical segments that form a clover leaf pattern
39
Aminoacylation
is the adding of a t-RNA molecule to an amino acid. Finished product is amino acetyl t-RNA, has 20 possible catalysts
40
RNA
Ribose sugar (OH group on 2') Single stranded
41
Wobble hypothesis
Allows the third base to change- this process is called redundancy
42
Telomeres
Non coding regions at the ends of chromosomes that preserve coding DNA from being lost during replication
43
VNTRs
Non- coding, repeating sequences of DNA. Variable number tandem repeats
44
LINEs
Repetitive DNA approximately 6500 bp in length long interspersed nuclear elements
45
SINEs
Repetitive DNA sequences approximately 500 bp i length. Short interspersed nuclear elements
46
Transpoon
Small segment of DNA that can move to a different position on the genome
47
Psedugene
A sequence of DNA that is similar to an existing gene but does not code for proteins
48
Ribosomal RNA
Binds with proteins to form the ribosomes, varies in length
49
retrovirus
enzyme called reserve transcriptase to transcribe its RNA genome into DNA The viral DNA is then incorporated into the host’s genome by an enzyme called integrase, then transcribed to produce virus proteins and viral RNA These proteins and RNA are used to assemble new virus particles
50
Viruses ability to enter a cell
use the cell’s reproductive enzymes provides scientists with a method for inserting new genetic material into an existing genome
51
viral vector
a virus that is used to transfer the DNA from a donor to a host
52
Transduction
is the use of viral vectors to introduce new genetic material into a cell (method of research) Researchers remove the harmful genetic material and replace it with the desired material
53
House keeping genes
Constantly expressed
54
Transcriptional regulation
regulates which genes are transcribed
55
Post transcriptional
mRNA undergoes changes in the nucleus
56
Translational
Controls how often and how rapidly mRNA transcripts will be translated into proteins
57
Post translational
Control the rate at which protein becomes active
58
Operon
Unit of transcription in prokaryotes Structural genes, promoter, operator
59
Lac operon
Repressor protein: A protein that binds to the operator (when no lactose is present) to prevent RNA polymerase from binding to the promoter and regulates the production of the lactose metabolizing proteins Lactose is the inducer
60
Trp operon
Uses a corepressor- binds to regulatory protein to reduce the expression of an operon's genes
61
Promoter
Initiates transcription of a certain gene
62
Operator
Region the regulatory factor binds to
63
ANti codon
3 t RNA bases that pair with a specific mRNA codon
64
mRNA
the end product of transcription- will be translated into a protein
65
tRNA
Carrier molecule that adds amino acids to the polypeptide chain
66
rRNA
an RNA molecule within the ribosome that bonds the correct amino acid to the polypeptide chain
67
pre-RNA
The initial RNA transcription product
68
Archibald Garrod
Alaptonuria "Inborn error of metabolism" Mutation of a gene that normally codes for a enzyme that breaks down the amino acid tyrosine First specific research between genes and metabolism
69
A site
Where amino acetyl tRNA binds 1
70
P site
Where poly peptide chain grows
71
E site
Where the t RNA leaves

Grade 12 bio (8 decks)

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