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General Biology I E4 > Chapter 17 > Flashcards

Chapter 17 Flashcards

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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

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2
Q

Gene Expression

A

the process by which DNA directs protein synthesis

two stages: 1) transcription 2) translation

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3
Q

2 stages of gene expression

A

1) transcription

2) translation

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4
Q

the study of metabolic defects …

A

provide evidence that genes specify proteins

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5
Q

Archibald Garrod

A

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

1909

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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

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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}

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8
Q

Genes code for …

A

polypeptide chains or for RNA molecules

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9
Q

RNA is…

A

the bridge to proteins (from DNA)

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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

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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

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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)

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13
Q

Ribosomes

A

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

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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

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15
Q

mRNA

A

can leave the nucleus and be translated by the ribosomes

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16
Q

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

A

DNA => RNA => protein

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17
Q

Genetic information is encoded

A

as a sequence of non overlapping base triplets or codons

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18
Q

DNA is a series of …

A

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

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19
Q

Codons

A

3 mRNA nucleotides that refer to a specific amino acid

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20
Q

During transcription, the gene determines…

A

the sequence of bases for an entire strand of mRNA

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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

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22
Q

Start Codon

A

AUG

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
Q

3 stages of Transcription

A

1) Initiation (find DNA)
2) Elongation (synthesis of growing RNA strand)
3) Termination (stop codon recognized)

26
Q

Promoters

A

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
Q

Transcription factors

A

help eukaryotic RNA polymerase recognize promoter sequences and start transcription

28
Q

Initiation in transcription

A

Promoters (TATA box)

Transcription factors

29
Q

During Elongation

in transcription

A

RNA polymerase moves along the DNA unraveling the double helix, for pairing with RNA nucleotides

30
Q

Termination mechanisms

in transcription

A

require the removal of RNA polymerase from the DNA and is different in prokaryotes and eukaryotes

31
Q

Enzymes in eukaryotic cells…

A

modify the mRNA in the nucleus after transcription for its dispatch to the cytoplasm

(proof-read) ?

32
Q

Translation

A

3 stages

1) Initiation
2) Elongation
3) Termination

into language of amino acids and polypeptides

33
Q

a cell translates or interprets…

in translation

A

a series of codons of an mRNA message into protein with the help of transfer RNA (tRNA)

34
Q

tRNA transfers

in translation

A

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
Q

Molecules of tRNA are not all identical

A

each carrie a specific amino acid on one end and has an anticodon on the other end to recognize the mRNA

36
Q

tRNA pairs…

A

with the codons of the mRNA to ensure the correct polypeptide is synthesized

37
Q

structure of tRNA

A

consists of a single RNA strand that is only about 80nucleotides long and is roughly L-shaped

38
Q

aminoacyl - tRNA synthetase

A

joins each amino acid to the correct tRNA, in an ATP-dependent manner

synthesizes the bond between an amino acid and tRNA

39
Q

Ribosomes facilitate

A

the specific coupling of tRNA anticodons with mRNA codons during protein synthesis

binds tRNA and facilitates protein synthesis

40
Q

ribosomal RNA or rRNA

A

are RNA molecules, along with proteins, that construct the ribosomal subunits

41
Q

Initiation in translation

A

brings together mRNA, tRNA bearing the first amino acid of the polypeptide, and two subunits of a ribosome

42
Q

Elongation in translation

A

amino acids are added one by one to the preceding amino acid

43
Q

Termination in translation

A

the final stage of translation and occurs when the ribosome reaches a stop codon in the mRNA

44
Q

Polyribosome

A

formed when a number of ribosomes can translate a single mRNA molecule simultaneously

help with speed and quantity

45
Q

A single protein can be translated

A

in less than 1 minute

46
Q

Completing and targeting the functional protein

A

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
Q

Mutations

A

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
Q

Point Mutations

A

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
Q

2 types of point mutations

A

1) Base-pair substitutions

2) Base-pair insertions or deletions

50
Q

Base-pair substitutions

A

replacement of one nucleotide and its partner with another pair of nucleotides

51
Q

Base-pair insertions or deletions

A

additions or losses of nucleotides pairs in a gene and may produce frameshift mutations

52
Q

Mutagens

A

physical or chemical agents that can cause mutations

i.e. UV, oxygen radicals, alkylating agents

53
Q

Genetic Code

A

and its associated machinery is nearly universal

is shared by organisms from the simplest bacteria to the most complex animals

54
Q

in laboratory experiments, genes can be

A

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”

General Biology I E4 (6 decks)

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