Biochemistry undergrad quiz (still making)

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Viruses contain either DNA OR RNA

1

A virus that is composed not of DNA but of RNA is called a

1

Viroids are infectious agents without protein

1

Prions –are infectious agents with both DNA and RNA

1

Adenine and guanine are

1

A nucleoside is formed when a
base is linked to the WHAT carbon of a
deoxyribose (or ribose) molecule

1

dCMP and dAMP are examples of ( nucleotides, nucleosides, proteins, nucleic acid )

1

In DNA and RNA, nucleotides are linked by phosphodiester bonds between the ❌ and 3′ carbons

2'

3'

4'

5'

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In all prokaryotes and eukaryotes DNA is double-stranded

1

Guanine and Cytosine form a base-pair held together by hydrogen bonds.
Adenine and Thymine form a base-pair held together by hydrogen bonds.

1

Most or all cellular DNA is A-DNA

1

Z-DNA is left handed and A-DNA is right handed

1

Underwinding generates supercoils
Overwinding generates supercoils

1

Single stranded DNA absorbs more UV than double
stranded DNA

1

UV absorbance rises as DNA
denatures is known as the

1

Tm (The temperature needed to denature
50% of the DNA molecules in a sample) is increased in DNA with high content of AT base-pairs

1

What are three key structural differences between
DNA and RNA?

1

Plasmids carry non-essential genes, e.g. for
antibiotic resistance

1

Bacterial genomes usually consist of a single, linear chromosome made of double-stranded DNA

1

Label this image

1

(Length of DNA/ Length of structure DNA packed into) is known as the

1

By mass, the composition of a chromosome at mitosis is
approximately

1

20% of amino acids are arginine or lysine

1

is a ring-shaped protein that can anchor the ends of a loop of DNA

1

is an enzyme that can remove supercoils from DNA

1

Acetylation removes positive charge from side-chain and so ❌
interaction between histones and negatively-charged DNA

strengthens

weakens

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Eukaryotic chromosomes have 1 origin of replication

1

In bacterial replication, replication begins at a single AT-rich origin and is
bidirectional

1

What enzyme carries out transcriptase?

1

To synthesise RNA, RNA polymerases require:

1

RNA polymerase binds to the promoter in the stage

1

RNA polymerase dissociates from DNA releasing
the new RNA molecule in the stage

1

RNA polymerase moves along the DNA molecule
synthesising an RNA copy in the stage

1

A sequence is a sequence of DNA having similar structure and function in different organisms.

1

The holoenzyme carries out elongation but not initiation

1

Eukaryotic promoters differ from those in bacteria

3

RNA polymerase ( I, ll, lll ) - synthesises rRNA
RNA polymerase ( I, ll, lll ) - synthesises tRNA
RNA polymerase ( I, ll, lll ) - synthesises mRNA

1

RNA polymerase II produces a 1° transcript (aka pre-mRNA)
which is processed in the nucleus to form mRNA. The main processing reactions are

1

Promoters recognised by RNA polymerase II usually consists of a core promoter that may include a ( TATA, TAAT, ATAT, ATTA ) box

1

RNA polymerases and DNA polymerases share the same mechanism.

1

By mass, ribosomes have about a 1:2 ratio of rRNA to protein

1

The size of ribosomes is measured in Svedbergs (S)
- sedimentation rate during centrifugation.

1

The small subunit on a ribosome catalyses peptide bond formation, the
large subunit binds the mRNA being translated

1

mRNA is read from

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The small (30S) ribosome subunit binds to the ribosome
binding site on the mRNA in E.Coli

1

There are several ribosome binding sites on mRNA in eukaryotes

1

A sequence has ❌ possible reading frames depending
on where translation starts from

three

one

two

four

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The region between an initiation codon (AUG) and a
termination codon is an“open-reading frame”

1

How do amino acids recognise codons?
Adaptor molecules deliver amino acids to the appropriate codons. These adaptors are transfer RNAs

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How long are tRNAs?

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All tRNAs have an anticodon

1

All tRNAs have the sequence GCA at their 3' end.

1

the ability of some bases at 5' end of anticodon to pair with more than one base at 3' end of codon is known as the

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The enzymes that link tRNAs to amino acids are called

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The classic example of inducible genes are the three genes required for utilisation of lactose by E. coli. These are:

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The is the binding
site for lac repressor
protein.

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The Lac gene encodes the
Lac repressor protein.

1

Transcription of the genes of the lac operon is repressed by the lac protein

1

When lactose is absent, the lac repressor protein binds to the promoter

1

When the lac repressor protein is bound to the operator,
RNA polymerase can still bind to the promoter but cannot
initiate transcription.

1

When lactose is present some is
converted into an isomer called
.

1

Allolactose binds to the lac repressor protein inducing a conformational change so that lac repressor cannot bind to operator.

1

Lactose breakdown is only necessary if glucose is not available. Therefore when both lactose and glucose are present in environment, lac operon genes only transcribed weakly. This effect is called Repression

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Removal of catabolite repression requires:

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When glucose conc’ is high the cAMP conc’ is low

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( Monosaccharides, Polysaccharides, Oligosaccharides ) are colourless, crystalline solids, water soluble and most are sweet tasting.

1

In general, a molecule with n chiral centres can have ( 2, 1, 3, 4 )n stereoisomers

1

Biochemistry Quiz am Biochemistry undergrad quiz (still making), erstellt von Lily O am 14/12/2019.

Biochemistry undergrad quiz (still making)

Viruses contain either DNA OR RNA

A virus that is composed not of DNA but of RNA is called a

Viroids are infectious agents without protein

Prions –are infectious agents with both DNA and RNA

Adenine and guanine are

A nucleoside is formed when a base is linked to the WHAT carbon of a deoxyribose (or ribose) molecule

dCMP and dAMP are examples of nucleotides nucleosides proteins nucleic acid( nucleotides, nucleosides, proteins, nucleic acid )

In DNA and RNA, nucleotides are linked by phosphodiester bonds between the ❌ and 3′ carbons

In all prokaryotes and eukaryotes DNA is double-stranded

Guanine and Cytosine form a base-pair held together by hydrogen bonds. Adenine and Thymine form a base-pair held together by hydrogen bonds.

Most or all cellular DNA is A-DNA

Z-DNA is left handed and A-DNA is right handed

Underwinding generates supercoils Overwinding generates supercoils

Single stranded DNA absorbs more UV than double stranded DNA

UV absorbance rises as DNA denatures is known as the

Tm (The temperature needed to denature 50% of the DNA molecules in a sample) is increased in DNA with high content of AT base-pairs

What are three key structural differences between DNA and RNA?

Plasmids carry non-essential genes, e.g. for antibiotic resistance

Bacterial genomes usually consist of a single, linear chromosome made of double-stranded DNA

A nucleoside is formed when a
base is linked to the WHAT carbon of a
deoxyribose (or ribose) molecule

dCMP and dAMP are examples of ( nucleotides, nucleosides, proteins, nucleic acid )

Guanine and Cytosine form a base-pair held together by hydrogen bonds.
Adenine and Thymine form a base-pair held together by hydrogen bonds.

Underwinding generates supercoils
Overwinding generates supercoils

Single stranded DNA absorbs more UV than double
stranded DNA

UV absorbance rises as DNA
denatures is known as the

Tm (The temperature needed to denature
50% of the DNA molecules in a sample) is increased in DNA with high content of AT base-pairs

What are three key structural differences between
DNA and RNA?

Plasmids carry non-essential genes, e.g. for
antibiotic resistance

By mass, the composition of a chromosome at mitosis is
approximately

Acetylation removes positive charge from side-chain and so ❌
interaction between histones and negatively-charged DNA

In bacterial replication, replication begins at a single AT-rich origin and is
bidirectional

RNA polymerase dissociates from DNA releasing
the new RNA molecule in the stage

RNA polymerase moves along the DNA molecule
synthesising an RNA copy in the stage

RNA polymerase ( I, ll, lll ) - synthesises rRNA
RNA polymerase ( I, ll, lll ) - synthesises tRNA
RNA polymerase ( I, ll, lll ) - synthesises mRNA