Reploication Flashcards Preview

Molecular and Cell Biology > Reploication > Flashcards

Flashcards in Reploication Deck (40)
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1
Q

What is translation?

A

The RNA directed synthesis of a polypeptide

2
Q

What interprets the code on an mRNA molecule?

A

tRNA

3
Q

What is the function of tRNA?

A

transfer amino acids from the cytoplasm to a ribosome

4
Q

How many amino acids are there?

A

20

5
Q

Are all tRNA molecules identical?

A

No, each codes for a particular mRNA codon in a particular amino acid

6
Q

On one end of the tRNA is the amino acid, what is at the other end?

A

Nucleotide triplet called an anticodon that base pairs with complementary codon of mRNA

7
Q

Where is tRNA transcribed?

A

From DNA in the nucleus

8
Q

What happens to the tRNA molecule once it has dropped an amino acid at the ribosome?

A

Recycled, goes to get another one

9
Q

What is a tRNA made of?

A

Single RNA strand, about 80 nucleotides long

10
Q

How does tRNA get its structure?

A

complementary stretches in the polypeptide can hydrogen bond

11
Q

Which end of the molecule does amino acid attach to?

A

3’ end

12
Q

What shape is tRNA?

A

3D Structure, 3 loops, l shaped

13
Q

What are the two recognition stages required for accurate translation?

A

Correct match between amino acid and tRNA and a correct match between the tRNA anticodon and mRNA codon.

14
Q

What enzyme is required to match up tRNA and amino acid?

A

Aminoacyl-tRNA synthetase

15
Q

How does the enzyme Aminoacyl-tRNA synthetase attach the tRNA and amino acid

A

active site of enzyme fits only a specific amino acid and tRNA combination, joins together by covalent bond using ATP hydrolysis

16
Q

How many different types of Aminoacyl-tRNA synthetase enzymes are there?

A

20

17
Q

How many different codons are there for amino acids?

A

61 different codons

18
Q

What can be seen from the fact that there are 61 different codons but 20 amino acids?

A

tRNA is able to bind to more than one different codon, wobbly base pairings, the third base pair rule is more relaxed

19
Q

What I the function of a ribosome?

A

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

20
Q

What is a ribosome built from?

A

rRNA, Small and large subunits

21
Q

Where is rRNA made?

A

In the nucleus from chromosomal DNA

22
Q

When do the large and small subunits attach?

A

Only join to form a functional ribosome when they attach to mRNA in the cytoplasm

23
Q

What is the most abundant type of cellular RNA?

A

rRNA

24
Q

What are the components of a nucleotide monomer?

A

nitrogenous base, sugar molecule, phosphate group

25
Q

What are the two families of nitrogenous bases?

A

pyrimidines and purines

26
Q

Which bases are pyrimidines?

A

Cytosine and Thymine and Uracil

27
Q

Which bases are purines?

A

guanine and adenine

28
Q

How do you differentiate between purines and pyrimidines?

A

Purines are larger, with 6 carbon ring fused to a five carbon ring, as opposed to a single six carbon ring

29
Q

What sugar is found in RNA?

A

Ribose

30
Q

What sugar is found in DNA?

A

Deoxyribose

31
Q

What is the difference between the sugar in DNA and RNA?

A

presence and absence of oxygen

32
Q

Which carbon is the phosphate group added to in the sugar of a nucleotide?

A

5’ carbon

33
Q

How are adjacent nucleotides joined?

A

Phosophodiester linkage

34
Q

What is a phosphodiester bond?

A

Phosphate group that links sugars of two nucleotides, one has a phosphate attached to the 5’ carbon, the other has a hydroxyl group on a 3’ carbon

35
Q

What specifies the sequence of a gene?

A

linear order of bases on a chromosome

36
Q

How is cellular DNA structured

A

Two polynucleotide chains, two sugar phosphate backbones run in antiparallel directions in a double helix, joined together by hydrogen bonds between bases

37
Q

What is the semi conservative model of replication?

A

New DNA molecule contains one parent strand and one daughter strand

38
Q

What is a nucleoside triphosphate?

A

A molecule with three phosphate groups

39
Q

Which end are nucleotides added to?

A

3’ end

40
Q

Where does replication begin?

A

Origin of replication