Biochemistry Exam Iv - The Genetic Code

Front 1

Relates information in the sequence of bases in DNA and RNA to the structure (amino acid sequence) of a protein

Back 1

Genetic code

Front 2

Carries the code in the form of codons (words)

Back 2

mRNA

Front 3

Interprets the code from the mRNA into amino acids, uses anticodons

Back 3

tRNA

Front 4

The machine that catalyzes deconding and peptide bond formation; translation

Back 4

ribosome

Front 5

Work with the ribosome, mRNA and tRNA to start, maintain and end the process

Back 5

Translation factors

Front 6

80-90% of the cellular energy is used for protein biosynthesis

Back 6

Uses GTP and ATP

Front 7

The ribosome, mRNA and charged tRNA's (each carrying an amino acid) must come together

Back 7

Ribosome must 'read' its way down the mRNA (5' to 3' only)

Uses tRNA's to translate nucleotide sequence into amino acid sequence

Front 8

Does the ribosome have reparative functions?

Back 8

Nope

Front 9

1. Correct mRNA sequence
2. Correct charginig of tRNA
3. Correct ribosome processivity
4. Correct start and stop

Back 9

Four determinants of fidelity.

Charging is responsible for most of the fidelity in RNA

Front 10

This RNA subunit has:
- a finger and thumb
- Palm position has peptidyl transferase activity.

Back 10

The large ribosomal subunit

Peptidyl transferase is a translocation domain.
- Information is read by tRNA's

Front 11

Symptoms:
- Reduced rate of RBC production
- Normochromatic macrocytic anemia
- Absence of erythroid precursors in normal marrow
- Elevated RBC Ad deaminase (eADA) and HbF

Back 11

Diamond Blackfan anemia

Craniofacial, hand, heart and urinary tract development defects.

Fetal/infant growth retardatio in severe (~40%) cases

Hint 11

Null mutation in genes coding for L5 or L11 (RPL5, RPL11)

L5 and L11 are large ribosomal subunits.

Increases incidence of cleft palate and thumb abnormalities

Front 12

1. Three tRNA binding sites
2. mRNA binding 'groove' between 40 S and 60 S
3. one active site (peptidyl transferase) in 60 S
4. Peptidyl trasnfer catalyzed by rRNA (ribozyme)
5. Adjacent tRNA sites lock into place the reading frame (in register)

Back 12

The functional architecture of the ribosome

Front 13

Amino acyl site (A) binding site on ribosome:

Back 13

Accepts tRNA

Front 14

Peptidyl (P) binding site on ribosome:

Back 14

Peptide bond is formed

Front 15

Exit binding site on ribosome:

Back 15

Penultimate tRNA bonds here.

Front 16

On the ribosome, mRNA binds on the groove between _____ S and the 60 S

Back 16

40

Front 17

The peptidyl transferase in ____ S possesses one active site

Back 17

60

Front 18

What enzyme is a ribozyme, not a protein?

Back 18

Peptidyl transferase

Large 28 S subunit

Front 19

Viral and bacterial mRNA's stall or nudge the ribosome to slip forward or back one or two nucleotides.

Causes frameshifting.

What does this allow the virus/bacteria to do?

Back 19

Allows for it to make two different proteins from one coding region.

Used by retroviruses (ie, HIV) to make gag-pol protein (viral replication)

Front 20

Which structure in gag-pol is synthesized by the viral genome?

Back 20

Pol

Front 21

Which structure in gag-pol is responsible for structure?

Back 21

Gag

Front 22

Not every nucleotide will be the same.

Overriden by majority

Back 22

Consensus

Front 23

Translation proceeds ___' to ___3'

Back 23

5'-3'

N to C

Front 24

Untranslated regions often bind proteins that regulate ________

Back 24

translation

If it is found on the 5' side, it is called the 5' UTR (also known as the Leader Sequence),

or if it is found on the 3' side, it is called the 3' UTR.

Front 25

- Use periods or spaces to separate codons in an OFR

- Untrasnlated regions and unused reading frames are not 'punctuated'

- Punctation does not occur in native mRNA's

- Punctation changes with insertions, deletions and stop codons

Back 25

Introns normally have stop codons inside of the coding region (aka ORF)

UAA
UAG
UGA

Front 26

If the first position in anticodon is inosine, this allows for pairing with what nucleotides?

Back 26

U:I

C:I

A:I

Front 27

Wobbly 3rd base allows for both __:U and ___:U pairing

Back 27

A:U

G:U

Front 28

Some amino acids are encoded by more than one codon

Back 28

Degenerate genetic code

Front 29

Genetic code is considered universal, same in most prokaryotes and eukaryotes

Back 29

However, mitochondrial code is slightly different.

Front 30

Mutations:

Nucleotide change does not alter protein sequence

Back 30

Silent mutation

Front 31

Mutations:

Nucleotide change alters the protein sequence by one AA

Back 31

Missence mutation

Little effect on protein function in most cases

Front 32

Mutations:

Nucleotdie change converts a sense codon to a stop codon

Back 32

Nonsense mutation

Truncates protein prematurely, loss of function

Front 33

Mutations:

Nucleotide change converts a stop codon to a sense codon

Back 33

Read-through mutation

Fusion protein (extension)

Effect depends on position of the next stop codon

Front 34

Mutations:

Insertion or deletion of 1, 2, 4, or 5 nucleotide changes in the reading frame

Back 34

Frameshift mutation

Incoherent protein sequence, truncates prematurely

Loss of function

Front 35

- Lipoprotein lipase deficiency (familial chylomicronemia)
- Severe unmanageable type V hyperlipoproteinemia
- Episodes of abdominal pain following high fat meals
- Obese heterozygotes may show fasting hypertriglyceridemia

Back 35

Frameshift mutation disease

Front 36

Sickle cell disease

Phenylketonuria

Back 36

Missense mutations

Front 37

B-thalassemia

Phenylketonuria (milder)

Back 37

Nonsense mutations

Front 38

Humans use RNA editing to introduce a nonsense codon. Give an example:

Back 38

Apo B48

In the intestine, deamination of C (into a U)in the middle of the mRNA creates a stop codon.

UAA