Test 2 Flashcards Preview

Biochem > Test 2 > Flashcards

Flashcards in Test 2 Deck (69)
Loading flashcards...
1

How many chromosome pairs do humans have

We each have 23 pairs of chromosomes

2

What type of bonds between histones and dna

Hydrophobic interactions and salt linkages

3

What prevalant amino acids are in histones and what charge do they give the protein?

Lys and arg make up 20% of histones AA’s and this gives it a + charge which is attracted to the slight negative charge of dna

4

What is a nucleosome

Basic unit of dna packaging where there is DNA and 8 histones all combined

5

What is chromatin

Protein + nuclear dna

6

Euchromatin is?

Lightly packed chromatin, usually in the areas of genes where there is often active transcription. (92% of our genes are euchromatin)

7

Heterochromatin is?

Very condensed chromatin. Basically genetically inactive. It is highly concentrated at centromeres and telomeres.

8

What is the position effect in regards to heterochromatin?

Activity of a gene depends on its position on a chromosome where heterochromatin is usually near telomeres and centromeres.

9

Percent of dna in exons

1.5%

10

99% of all introns begin with what and end with what?

Begin - GT
End - AG
GET EGG

11

What is histone deacetylase and histone acetyltransferase ?

HDAC pulls off acetyl groups from histones and acetyltransferase puts them on histone.

12

Why does it matter if the histone is acetylated or not?

Being acetylated causes the Dna to be less tightly wound around the histones. This means that the dna on the histone area will be transcribed.

13

Silent mutation

No change in AA coded for

14

Missense mutation

Change in AA but no change in protein function

15

Nonsense mutation

Changes it to a premature stop codon

16

Frameshift mutation

One or more nucleotide are deleted or inserted that causes the codons to be read out of frame.

17

What causes sickle cell anemia genetically speaking

Missense mutation in 6th codon in hbb - substitutes valine (hydrophobic) to Glu (neg charged and Hydrophilic ) messes up RBCs By forming rigid rod like proteins

18

What 2 ways does sickle cell anemia decrease o2 carrying of cells

Poor o2 capacity and clog capilaries

19

Duchenne muscular distrophy

Large in frame and out of frame deletions to the dystrophin gene.
Oof - deletion leads to little to no expression of the gene - severe form of disease - causes muscles to waste away
If- deletion gives milder form of disease

20

Structure of mRNA

5’ 7-methylguanosine cap.
Poly A tail
Untranslated region before and after the coding region.

21

What is tRNA structure

Cloverleaf shape
2 unmatched nucleotides are vital for function
The anticodon loop which binds codons
And the 3’ CCA region that binds the corresponded AA to the codon

22

What is an aminoacyl tRNA

Complex of AA with tRNA
AA needs to be activated by aminoacyl tRNA synthetases
Each AA has its own synthetase - these serve as second genetic code

23

Human ribosomes are what size?

60s and 40s
80 S total

24

3 sites on ribosomes

APE
Acceptor site
Peptidyll
Exit

25

Creutzfeldt-jakob disease

Misfolding of prion proteins - transmissible ; prions can cause other proteins to misfold
Belongs to transmisible spongiform encephalopathies

26

Huntingtons disease

Mutation in huntingtons gene results in expansion of CAG triplet repeats
Results in polygln repeats
Selective death of cells in basal ganglia cause symptoms

27

Parkinsons disease

Agregation of alpha-synuclein which deposit lewy bodies in dopaminergic neurons in substantia nigra
Symptoms from reduuction in dopamine availability
AS mutations cause familial parkinsons
Brain aging is the common denominator for non familial

28

Alzheimers disease

APP amyloid precursor protein breaks down to form Amyloid beta peptide. Misfolding of ABeta forms plaques in brain
Hyperphosphorylationof tau - neurofibrilary tangles
APP and Tau mutations cause familial versions
Brain aging is common denominator of sporadic form

29

Proteins such as histones are typically acetylated on what residue and with what?

On lysine residues with acetyl coa used at the acetylator

30

Protein disulfide isomerases do what

Help formation and reorganization of disulfide bonds between cysteine residues in the ER lumen,