Chapter 17 Flashcards

1
Q

what form is the content of DNA in?

A

specific sequences of nucleotides that is inherited by an organism and leads to specific traits by dictating the synthesis of proteins

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

Gene Expression

A

the process by which DNA directs protein synthesis

two stages: 1) transcription 2) translation

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

2 stages of gene expression

A

1) transcription

2) translation

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

the study of metabolic defects …

A

provide evidence that genes specify proteins

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

Archibald Garrod

A

first to suggest that genes dictate phenotypes through enzymes that catalyze specific chemical reactions in the cell

1909

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

Beadle and Tatum

A

developed the “one gene-one enzyme theory”

cause bread mold (neurospora cassia) to mutate with X-rays creating mutants that could not survive on minimal medium

1930s

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

“one gene-one enzyme theory”

A

states that the function of a gene is to dictate the production of a specific enzyme

DNA => RNA => protein (enzymes)
* not all proteins are enzymes {i.e. actin and tubuline}

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

Genes code for …

A

polypeptide chains or for RNA molecules

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

RNA is…

A

the bridge to proteins (from DNA)

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

Transcription

A

the synthesis of RNA under the direction of DNA that produces messenger RNA (mRNA)

the DNA-directed synthesis of RNA

the conversion of DNA into RNA

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

Translation

A

the actual synthesis of a polypeptide which occurs under the direction of mRNA and occurs on ribosomes

the conversion of nucleotide (RNA) into polypeptide

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

Gene expression in Prokaryotes

A

lack a nuclei, so transcription and translation occur together
DNA => RNA => protein

Ribosomes help: attach to the leading end of mRNA and start translating while transcription is still in progress (to synthesize proteins)

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

Ribosomes

A

attach to the leading end of mRNA and start translating while transcription is still in progress (to synthesize proteins)

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

Gene expression in Eukaryotes

A

RNA transcripts (primary transcripts) are made in the nucleus are modified before becoming true mRNA

mRNA will leave the nucleus and be translated by the ribosomes

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

mRNA

A

can leave the nucleus and be translated by the ribosomes

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

Genetic Code: Cells are governed by a cellular chain of command

A

DNA => RNA => protein

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

Genetic information is encoded

A

as a sequence of non overlapping base triplets or codons

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

DNA is a series of …

A

3-nucleotides with instructions for RNA and a specific polypeptide chain

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

Codons

A

3 mRNA nucleotides that refer to a specific amino acid

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

During transcription, the gene determines…

A

the sequence of bases for an entire strand of mRNA

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

Condon in mRNA

A

either translated into an amino acid or serves as a translational stop signal (codon).

must be read in the correct reading frame for the specified polypeptide to be produced

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

Start Codon

23
Q

Stop Codon

A

UGA

UAG
UAA

24
Q

Components of Transcription

A

RNA synthesis is catalyzed by the enzyme RNA polymerase, which opens the DNA strands and hooks together the RNA nucleotides (5’ - 3’)

RNA follows the same base-pairing rules as DNA, excepted that in RNA, uracil substitutes for thymine

25
3 stages of Transcription
1) Initiation (find DNA) 2) Elongation (synthesis of growing RNA strand) 3) Termination (stop codon recognized)
26
Promoters
sequences of DNA that signal the initiation of RNA synthesis i.e. TATA box: rich in A and T and is located about 25nucleotide upstream of the transcription start site
27
Transcription factors
help eukaryotic RNA polymerase recognize promoter sequences and start transcription
28
Initiation in transcription
Promoters (TATA box) | Transcription factors
29
During Elongation | in transcription
RNA polymerase moves along the DNA unraveling the double helix, for pairing with RNA nucleotides
30
Termination mechanisms | in transcription
require the removal of RNA polymerase from the DNA and is different in prokaryotes and eukaryotes
31
Enzymes in eukaryotic cells...
modify the mRNA in the nucleus after transcription for its dispatch to the cytoplasm (proof-read) ?
32
Translation
3 stages 1) Initiation 2) Elongation 3) Termination into language of amino acids and polypeptides
33
a cell translates or interprets... | in translation
a series of codons of an mRNA message into protein with the help of transfer RNA (tRNA)
34
tRNA transfers | in translation
amino acids from eh cytoplasmic pool to a ribosome and the ribosome adds (catalyzes) each amino acid carried by tRNA to the growing end of the polypeptide chain
35
Molecules of tRNA are not all identical
each carrie a specific amino acid on one end and has an anticodon on the other end to recognize the mRNA
36
tRNA pairs...
with the codons of the mRNA to ensure the correct polypeptide is synthesized
37
structure of tRNA
consists of a single RNA strand that is only about 80nucleotides long and is roughly L-shaped
38
aminoacyl - tRNA synthetase
joins each amino acid to the correct tRNA, in an ATP-dependent manner synthesizes the bond between an amino acid and tRNA
39
Ribosomes facilitate
the specific coupling of tRNA anticodons with mRNA codons during protein synthesis binds tRNA and facilitates protein synthesis
40
ribosomal RNA or rRNA
are RNA molecules, along with proteins, that construct the ribosomal subunits
41
Initiation in translation
brings together mRNA, tRNA bearing the first amino acid of the polypeptide, and two subunits of a ribosome
42
Elongation in translation
amino acids are added one by one to the preceding amino acid
43
Termination in translation
the final stage of translation and occurs when the ribosome reaches a stop codon in the mRNA
44
Polyribosome
formed when a number of ribosomes can translate a single mRNA molecule simultaneously help with speed and quantity
45
A single protein can be translated
in less than 1 minute
46
Completing and targeting the functional protein
polypeptide chains undergo further modifications after the translation process (post-translation modification) that affects their shape, function, or destination in the cell proteins destined for the endomembrane system or secretion must be transported and synthesized directly into the ER these proteins have signal peptides enabling the translating ribosome to bind to the ER and synthesize into the ER center i.e. insulin important words: 1) post-translation modification; 2) endomembrane system; 3) signal peptides SRP: signal recognition protein after signal peptide: brings ribosome to ER
47
Mutations
in nucleic acids can affect protein structure and function changes in the genetic material of the cell can occur during DNA or RNA replication, recombination, or repair
48
Point Mutations
changes in one base pair of a gene that leads to the production of an abnormal protein i.e. sickle cell disease change from CTT (Glu) => CAT (Val)
49
2 types of point mutations
1) Base-pair substitutions | 2) Base-pair insertions or deletions
50
Base-pair substitutions
replacement of one nucleotide and its partner with another pair of nucleotides
51
Base-pair insertions or deletions
additions or losses of nucleotides pairs in a gene and may produce frameshift mutations
52
Mutagens
physical or chemical agents that can cause mutations i.e. UV, oxygen radicals, alkylating agents
53
Genetic Code
and its associated machinery is nearly universal is shared by organisms from the simplest bacteria to the most complex animals
54
in laboratory experiments, genes can be
transplanted between organisms or species then these genes can be transcribed and translated to make the same proteins i.e. tobacco plant expressing firefly genes causes the plant to "glow"