Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

New > deck_6622634 > Flashcards

deck_6622634 Flashcards

(59 cards)

Start Studying
1
Q

Gene expression-

A

steps in which DNA in the genes code for proteins

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

Archibald Garrod-

A

studied rare genetic disease called alkaptonuria

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

alkaptonuria

A

recessive disease in which affected individuals were unable to break down tyrosine, an amino acid. Instead, homogentisic acid accumulates in urine andturns it black. Lacked the enzyme which breaks down homogentisic acid–Mutation in one gene is associated with the absence of this specific enzyme

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

Beadle and Tatum-

A

studied the fungus Neurospora.

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

Neurospora Wild Type

A

individual with normal phenotype, which can grownormally on simple growth medium/basic nutrients

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

Mutant strain (produced by radiation)- Neospora

A

cannot make a substance such as an amino acid, can only grow if that substance is added to growth mediumo Each mutant strain had mutation at only one locus- each gene locus affected only one enzymeCalled this the one-gene, one-enzyme hypothesis

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

Linus Pauling-

A

Mutation at single locus alters the structure of one polypeptide chain of hemoglobin, causing sickle cell anemiao Therefore- we now conform to the one-gene, one-polypeptide chain hypothesis

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

Ribonucleic acid, or RNA,

A

link between DNA to protein

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

Differences between RNA and DNA:

A

o RNA is single strandedo Contains the sugar ribose, not deoxyriboseo Base uracil substitutes for thymine

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

Transcription-

A

the “copying” of the template strand of DNA and formation of RNA. Forms three types of RNA

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

three types of RNA

A

mRNA, tRNA, rRNA

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

Messenger RNA (mRNA)-

A

single, uncoiled strand of RNA that carries information for making a protein

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

Transfer RNA (tRNA)-

A

single strand of RNA that folds backon itself to form a specific shape. Each tRNA bonds toone type of amino acid and carries it to the ribosome

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

Ribosomal RNA (rRNA)-

A

globular RNA that is part of the ribosomes of RNA and helps catalyze protein synthesis

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

Differences between transcription and DNA replication:

A

Only part of the DNA molecule isused as a templateo EnzymeRNA polymerase is used as opposed to DNA polymeraseo Results in one free RNA strand, not a double helixTranscription happens constantly–DNA replication happens during S of cell cycle

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

Initiation: (transcription)

A

first stage of transcriptiona. RNA polymerase attaches to promoter- region inDNA that is not transcribed, contains the sequenceTATA (TATA box)b. RNA polymerase then unwinds the DNA and initiates transcription

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

Elongation: (transcription)

A

second stage of transcriptiona. RNA polymerase assembles RNA nucleotides using1 strand of the DNA as a templateb. Occurs in5’ to 3’ direction (new strand is made in 5’ to 3’ directionlike in replication)

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

Termination: (transcription)

A

third stage of transcriptionRNA polymerase reaches a special sequence ofnucleotides that serve as a termination pointIn eukaryotes- often contains the DNA sequence AAAAAAARNA polymerase releases the DNA template and the new RNA strand

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

In eukaryotic cells, each new molecule of mRNA is only what? what does this necessitate?

A

“pre-mRNA”- must be modified before it can code for proteins

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

Modification of mRNA–5’ end

A

A modified GTP (guanosine triphosphate- or a guanine nucleotide with two extra phosphate groups) is added to the 5’ end to form a 5’ cap. Provides stability to new mRNA and a point of attachment for the ribosome.

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

Modification of mRNA–3’ end

A

3’ end of mRNA- 150 – 200 adenine nucleotides are added- poly-Atail (-A-A-A….A-A-3’)o Provides stabilityo Controls movement of mRNA across the nuclear envelope

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

heterogenous nuclear RNA,

A

Pre-mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Alternative splicing-

A

Different exons can be kept in or snippedout- will change the types of proteins that are produced. Explains how human cells can make hundreds ofthousands of proteins from only about 20k genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Exons-

Study These Flashcards
A

sequences that express a code for a polypeptide. exported from nucleus.

25
Introns-
intervening base sequences that must be removed before translation--stay in the nucleus
26
Small nuclear ribonucleoproteins, or snRNPs,
delete out the introns and splice the exons
27
Translation-
information found in mRNA is used to specify the amino acid sequence ofa polypeptide
28
codons
The mRNA is read as codons- sequences of three consecutive bases of mRNA which specifies one amino acid
29
codon code
Code is called triplet code because each codon consists of three nucleotides. All of the codons collectively form the genetic code
30
cracking of genetic code
By 1967, the genetic code was “cracked”- scientists hadidentified the amino acids for all 64 possible codons. The genetic code is universal- the same codons code for the same amino acids in all organisms. Since there are 64 possible codons and only 20 amino acids,more than one codon specify certain amino acids
31
anticodon
A particular tRNA can recognize a specific codon because it has a sequence of three bases, called the anticodon, that is complementary to the mRNA codon, forming hydrogen bonds with one another.
32
Wobble effect-
The codon- anticodon interactions are not as strong for the third base in a codon
33
Stop codons
UAA, UAG, UGA
34
start codons
AUG
35
effect of binding of anticodon
The amino acids carried by the tRNA can then be linkedtogether by peptide bonds in the order specified by the sequence of codons in the mRNA.
36
Ribosomes
the site of translationConsist of two subunits, small and largeEach is made of proteins and rRNADuring translation, the mRNA molecule fits between the two subunitsContain 2 binding sites for tRNA: P, A, (and E)
37
Translation
mRNA moves out of nucleus to the cytoplasm. Requires the coordinated functioning of protein and RNA components of the ribosomes, mRNA, and amino acids linked to tRNAs.
38
tRNA action translation
Folds on itself to form three or more loops of unpaired nucleotidesBottom loop contains an anticodon- 3 bases at bottom of molecule that will complementary base pair with thecodon found on the mRNAEach kind of tRNA binds to a specific type of amino acid at the three prime top of the moleculeSEE DIAGRAM
39
P site-
peptidyl site-tRNA holding growing polypeptide chain binds here
40
A site-
aminoacyl site- tRNA delivering the next amino acid in the sequence binds here
41
E site-
Exit site--tRNA exits here after dropping off its amino acid
42
Initiation-SEE DIAGRAM
first stage of translation:The small ribosomal unit binds to the five prime end of the mRNAAn initiator tRNA binds to an mRNA at the startsequence AUG. The initiator tRNA carries with it theamino acid met The large ribosomal unit binds to the small unit. Theinitiator tRNA occupies the P site
43
initiation complex
ribosome + mRNA + tRNA
44
Elongation-SEE DIAGRAM (translation)
second stage of translation: a. A new tRNA bearing an amino acid binds to the A site of the ribosome. b. Methionine is removed from the first tRNA andattaches to the amino acid on the newly arrived tRNA That first tRNA is then released into the cytoplasmwhere it can once again bind to its amino acid. Meanwhile, the second tRNA can now move from the A site into the vacated P site. The A site is now open, exposing the next codon. A new tRNA carrying a new amino acid enters the A site.( The two amino acids in the P site bind to this new amino acid, forming a chain of 3 amino acids. This continues over and over, and the chain elongates by one amino acid at a time- dictated by the codons in the mRNA.)
45
Termination-SEE DIAGRAM
Ribosome encounters a “stop” codon. No tRNA molecule bindsInstead, a release factor (special protein) binds to A siteTherefore, when the tRNA in the P site separates fromthe amino acid, the newly synthesized polypeptide chain is free
46
What happens after translation has completed?
amino acids of the polypeptide chain can associate to form secondary and tertiary structures
47
polysomes-
clusters of many ribosomes translating an mRNA transcript at the same time. found in bacterial cells that rapidly use or secrete proteins.
48
Mutation-
change in the nucleotide sequence of DNA. not every mutation causes an observable change (some codons code for same amino acids, change in eye color in an skin cell). Mutations provide diversity
49
Base substitution-
change in only one pair of nucleotides
50
Missense mutations-
Base substitution. replacement of one amino acid by anotherCan alter active site of enzymes
51
silent mutation-
Base substitution. codes for the same amino acid/no observable change
52
Nonsense mutations-
Base substitution. convert a code for an amino acid into a stop codon correct protein can't be produced
53
Frame shift mutation-
one or two nucleotide pairs are inserted ordeleted from the molecule, altering the reading frame (sometimes more --not multiples of 3) Codons downstream from this mutation specify a new sequence of amino acids resulting in a new polypeptide chain
54
Transposons, or transposable genetic elements-
DNA sequences that jump from one area into the middle of a geneCan alter the timing of the gene or block its activityDiscovered by Barbara McClintock- noticed that certain genes in corn would spontaneously turn on or offTransposons require an enzyme transposase for incorporation into a new locationMost are retrotransposons
55
retrotransposons
form copies of itself by producing an RNA intermediate, then an enzyme called reverse transcriptase forms DNA from that RNA and the DNA jumps into a gene
56
Causes of Mutations
Spontaneous or mutagens
57
Spontaneous mutations
Mistakes inDNA replication• Defects inmitotic or meiotic separation• Hot spots
58
Hot spots-
areas of DNA that are more likely than others to mutate--generally areas that have stretches of repeated nucleotides
59
Mutagens-
anything that causes a mutation* Radiation• Chemical mutagens can modify bases, leading tomistakes in base pairing- Although mutations in the somatic cells cannot be passed on to offspring,some mutations can lead to cancer. In addition, many mutagens arecarcinogens-agents that can cause cancer

New (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions