DNA,Genes & Protein Synthesis Flashcards

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1
Q

Gene definition

A

Section of dna that contains the coded information for making polypeptides and functional RNA

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2
Q

Locus definition

A

Gene located at a particular position on DNA molecule

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3
Q

Explain Degenerate DNA

A

Most amino acids are coded by more than one triplet of bases - this is useful because some mutations may not affect the polypeptide chain and hence enzyme structure.

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4
Q

Non - overlapping DNA

A

A triplet is always read in one direction hence each base in a sequence is only read once so less likely mutations occur?

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5
Q

Universal DNA

A

same system in most organisms so indirect evidence for evolution

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6
Q

In eukarya most DNA are coding/ non - coding - produce mRNA with introns and exons?

A

Non coding (introns)

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7
Q

Differences between prokaryotic and eukaryotic dna MOLECULES

A

Pro is shorter euk is longer
Pro can firm circular dna and plasmids euk is linear
Pro is not associated with proteins euk is associated with histones

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8
Q

Describe how a DNA molecule and it’s associated proteins form a chromosome and benefit

A

Chromosomes appear as two threads. Each thread is called a chromatid. DNA in chromosomes are held together by histones - looped aroudn histones and tightly coiled so a lot of DNA is condensed into a single histone.

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9
Q

Chloroplasts and mitochondria also contain DNA - what type and describe

A

Prokaryotic dna

Short, circular and not associated with proteins

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10
Q

Explain how a sequence of three bases code for a specific amino acid

A

Three bases are transcribed into a codon, which is specific to an amino acid that is complementary to the anticodon of tRNA

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11
Q

Genome definition

A

The complete set of genes in a cell

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12
Q

Proteome definition

A

The full set of proteins a cell is able to produce.

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13
Q

Homologous pairs

A

Maternal and paternal chromosomes

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14
Q

Allele definition

A

One of a number of alternative forms of a gene.

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15
Q

Two types of rna important to protein synthesis are

A

mRNA

tRNA

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16
Q

RNA (both types) are polymers made of mono nucleotides. What is the structure of the nucleotide

A

Ribose bonded to a phosphate group and organic bases adenine cytosine guanine and uracil

17
Q

mRNA structure

A

Single long strand arranged in a single helix

18
Q

DNA vs mRNA structure

A

DNA is double stranded alpha helix, mRNA is a single stranded helix
mRNA has uracil instead of thymine
Ribose vs deoxyribose in dna

19
Q

tRNA structure

A

80 nucleotides
Single stranded chain folded into clover shape with one strand extending beyond the other
Paired bases inside present so hydrogen bonding
Unpaired based on outside
Specific amino acid binding site
Amino acid is complementary to anticodon at opposite end
Anticodon is complementary to mRNA codon

20
Q

Transcription process

A

RNA polymerase unzips and unwinds the part of the DNA molecule needed by breaking hydrogen bonds between complementary base pairs. This is a local unwinding of molecule only where needed.
Exposed nucleotides on template strand attract free activated RNA nucleotides from from the cytoplasm/ nucleoplasm?
As RNA polymerase moves along the DNA strands, it catykses the formation of phosphodiester bonds between RNA nucleotides.
Enzyme zips molecule up behind it (reforms hydrogen bonds)
Forms pre - mRNA

21
Q

Splicing in eukaryotes or prokaryotes?

A

Eukaryotes

22
Q

Splicing

A

Pre - mRNA strand has introns which are non - coding regions. Before leaving nucleons, introns are cut out and exons are joined together by a mature mRNA, which leaves the nucleus through nuclear pore.

23
Q

In prokaryotes transcription results in the

A

Direct formation of mRNA

24
Q

How does tRNA become charged?/ use of ATP in translation

A

Specific enzyme binds to ATP and specific amino acid
ATP loses two phosphate molecules becoming AMP and specific tRNA molecule is recruited.
tRNA covalently bonds to amino acid and AMP is released
ATP provides energy for covalent bond to form

25
Q

Translation

A

Ribosome attaches to mRNA at start codon.
Charged tRNA molecule contains complementary anticodon and its specific amino acid
Anticodon is attracted to exposed base pairs of mRNA
Charged tRNA with complementary anticodon pairs with next codon on mRNA
Two tRNAs are sitting next to each other in ribosome sites
Enzyme activity within the large ribosome sub unit joins the amino acids using ATP for peptide bond formation
First tRNA molecule is uncharged and leaves ribosome to find specific amino acid againand the next charged tRNA molecule enters ribosome site
Ribosome detaches from polypeptide chain upon reaching stop codon. Ribosome, tRNA and mRNA all separate now.
Polypeptide chain folds into secondary and tertiary structure.

26
Q

Is mRNA a “forever” molecule

A

No breaks down easily to prevent over synthesis of proteins

27
Q

Ribosomes formed?

A

Translation but specify two subunits

28
Q

DNA is an info carrying molecule explain

A

Genetic information and instructions on protein synthesis

29
Q

RNA is an info carrying molecule

A

Transfer DNA genetic instructions to ribosomes to form polypeptide chains