DNA Structure Flashcards Preview

MCBG > DNA Structure > Flashcards

Flashcards in DNA Structure Deck (19)
Loading flashcards...
1
Q

Different between structure and function of eu and heterochromatin?

A

Eu - white, in bead on string form as can be actively being transcribed/expressing genes
Hetero - black, solenoids, unable to be expressing genes. ONLY IN EUKARYOTES

2
Q

What is the DNA double helix formed of?

A
  • Phosphate group
  • Deoxyribose sugar
  • Nitrogenous Base (GTAC)
3
Q

What is the use of DNA packing?

A

It’s too large to fit in the nucleus otherwise

4
Q

What is the breakdown of structure of chromatin?

A

Double helix wrapped around histones, form solenoids (hetero).

5
Q

What is a solenoid?

A

Double helix DNA wrapped round histone proteins.

6
Q

What is a nucleosome?

A

One ‘bead on the string’ ie DNA round a histone core

7
Q

Do chromosomes express genes?

A

No

8
Q

What is the definition of a gene?

A

The code for a protein in triplet code.

9
Q

Where are genes located?

A

Genes have a specific chromosomal location

10
Q

How many genes do humans have? What is the genome?

A

Around 25000, all cells have all genes, phenotype differs

11
Q

Define and name bases, nucleosides and nucleotides for DNA and RNA

A

Bases - Adenine, Guanine, Cytosine, Thymine/Uracil

Nucleosides - Base + Sugar e.g. Deoxyadenosine/Adenosine

Nucleotides - Base + Sugar + Phosphate - deoxyadenosine monophosphate, diphosphate, triphosphate. (dAMP or AMP etc)

12
Q

What is the difference between ribose and deoxyribose?

A

Loss of O on carbon 2 deoxyribose (bottom right corner)

13
Q

How is a phosphate attached to a deoxyribonucleotide?

A

Phosphodiester bond on carbon 5

14
Q

What is the difference in structure between purines and pyrimidines?

A

Pyrimidines have one aromatic (carbon nitrogen) ring, purines have 2.

15
Q

Name the two purines and two pyrimidines

A

Purines - adenine guanine

Pyrimidines - cytosine, thymine

16
Q

If Guanosine is the nucleoside what is the nucleotide for DNA and RNA?

A

dGMP/dGDP/dGTP

GMP/GDP/GTP

17
Q

If dCMP and CMP are the nucleotides what are the nucleosides

A

Cytidine

18
Q

What is at the 5’ and 3’ of DNA?

A

5’ - phosphate

3’ - OH

19
Q

How do G+C and A+T(U) base pair? How many bonds?

A

G+C have 3 x O-H bonds

A+T(U) have 1 x O-H and 1 x N-H bonds