DNA and Protein synthesis Flashcards

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1
Q

What is the structure of a nucleotide

3 points

A

1) It is made of a pentose sugar; phosphate and nitrogenous base
2) It is held together by covalent bonds
3) It has a phosphodiester and glycosidic bond

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2
Q

What are the key features of nucleotides?

4 points

A

1) they become phosphorylated when they contain more then one phosphate group
2) Form the monomer of nucleic acids = DNA and RNA
3) Help regulate metabolic pathways i.e ATP; ADP
4) May be components of co- enzymes

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3
Q

What is the structure of DNA?

4 points

A

1) Polymer made up of many nucleotides
2) Consists of two polynucleotide strands that form a double helix
3) The strands are antiparrallel are in a ‘5 3’ formation
4) Tightly wound around histone proteins in chromosomes

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4
Q

Why does the purine always pair with the pyrimidine?

A

It gives equal size rungs on the DNA ladder that form the double helix and helps enable stability

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5
Q

What is the key word to describe chromosomes if there identical?

A

Homologus

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6
Q

What are the key features of genes?

3 points

A

1) Sections of DNA
2) Codes for a particular characteristic
3) alternate forms of the gene arising in mutations are called alleles

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7
Q

How many bonds does adenine and thymine form?

Cytosine and guanine?

A

A and T = 2
C and G = 3
these are held together by hydrogen bonds

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8
Q

What is the formation of the double helix?

A

5’ 3’ from the 5 prime end (phosphate attached to the 5th carbon) to the 3 in an antiparrallel structure

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9
Q

What are the purines and what are the pyrimidines and what are there structures?

A
Purine = A + G = double ringed structure
Pyrimidines = C + T = single ringed structure
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10
Q

What are the differences between DNA and RNA

4 points

A

1) RNA is single stranded
2) It uses uracil instead of thymine
3) It is made from ribosomes
4) it is oxygenated

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11
Q

What does the glycosidic and phosphodiester bond require?

A

A condensation reaction

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12
Q

What is semi conservative, conservative, dispersive?

A

Semi conservative = One new daughter strand and one complementary to the parent strand
Conservative = entirely new / entirely old
Dispersive = Dotted DNA molecules all broken up

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13
Q

What enzymes are involved in DNA replication and what are there functions?

A

Gyrase - unwinds DNA
Helicase - unzips DNA = hydrogen bonds are broken
Primase - Signals where the nucleotides are added
DNA polymerase- adds the nucleotides in a 5’ 3’ direction
DNA Ligase - sticks the lagging strand fragments

Good Hearts Pour Pots of Love

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14
Q

Which is the leading and lagging strand?

A
5'-3' = leading 
3'-5' = lagging
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15
Q

What are okazaki fragments

A

Short sequences of DNA nucleotides which are synthesized discontinuously on the lagging strand during DNA replication.
This happens as only a certain amount of the lagging strand can unzip before it can be synthesized further

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16
Q

What supplies the energy for phosphodiester bonds?

A

Hydrolysis of nucleotides activates them to release extra phosphate groups

17
Q

Mutations

3 points

A

1) Occurs in 1 to 10(8) base pairs/ every 100,000 nucleotides
2) During replication enzymes can be proof read editing out the incorrect nucleotides, reducing the rate of mutations
3) Different versions of the genes are called alleles

18
Q

What is the process of transcription?

3 points

A

1) RNA polymerase binds to DNA strand and unwinds a short section (about 12 pairs long)
2) This then travels along the DNA strand building an RNA molecule from the template strand
3) Non coding strands of mRNA (introns) are cut out just leaving coding strands( exons) in a process called splicing

19
Q

What is translation?

A

The process by which the mRNA is read to produce a protein chain

20
Q

What is tRNA ?

A

1) short strand of RNA
2) Carries the anti-codon which matches up to a codon
3) There are 64 tRNA molecules for each combination of bases

21
Q

How does tRNA work?

A

The tRNA anticodons link to the right codon of the mRNA. The amino acid is then made and then drop off next to other amino acids forming a chain held together by peptide bonds. These then fold into a complex 3D shape to form a protein

22
Q

How does RNA polymerase begin?

A

It attaches to the part of the gene called the promoter then separates the strand and starts to code for RNA

23
Q

What stops the polymerase?

A

The terminator

24
Q

What will the mRNA look like?

A

the mRNA will be pre- mRNA till the introns are spliced out and all is left is the exons, the guanine and the poly A tail

25
Q

What is the start codon?

A

AUG

26
Q

What are the different sites in translation?

A

P site= where the polypeptide chain forms
A site= open for new amino acid
E site= where it goes when it is ready to exit

27
Q

Universal definition

A

The same triplet of DNA bases codes for the same amino acid

28
Q

Degenerate definition

A

There are more then three bases that will code for an amino acid

29
Q

Non overlapping definition

A

Reading starts from a fixed point in groups of three bases.

If a base is added/deleted it causes a frame shift and every amino acid coded for will change

30
Q

How do nucleotides join together?

How would you break the bond?

A

By a phosphodiester bond when it forms water is released and a condensation reaction occurs
A hydrolysis reaction = adding back water= will reverse this

31
Q

What is the formation of ATP?

A

Base= adenine
Sugar = ribose
Phosphate = x3
The phosphate is negatively charged = unstable = low activation energy

32
Q

How does ATP work in increasing your energy?

A

When the bonds are hydrolysed they release considerable amounts of energy

33
Q

What is a dinucleotide ?

A

Two nucleotides joined together by a condensation reaction

34
Q

What are the differences between 5’ and 3’ strands?

A
5' = terminal phosphate group 
3' = terminal hydroxyl group
35
Q

mRNA

A

Transcribed from DNA, carries a copy of the genetic instructions from DNA to ribosomes in the cytoplasm where it is translated into a polypeptide chain

36
Q

tRNA

A

Carries amino acids to the growing polypeptide chain. On the end of the tRNA it carries the genetic code in a three nucleotide sequence called the anti codon. These amino acids link to the 3’ end of the tRNA

37
Q

rRNA

A

Forms ribosomes and assembles amino acids in polypeptide chain

38
Q

What showed Watson and Crick that DNA had a double helix?

A

There were gaps in the X pattern

39
Q

Why would a mismatch in nucleotides be unlikely to occur?

A

The number of hydrogen bonds each base has

There different sizes