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Flashcards in General Qs for MCBG Deck (60)
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1
Q

Which bond forms between sugar and base?

A

Glycosidic

2
Q

Where are phosphodiester bonds formed?

A

Between sugar and phosphate

3
Q

Which end 5’ or 3’ makes new phosphodiester bonds in DNA replication?

A

3- OH end

4
Q

Which base pairs form 3 hydrogen bonds and which form 2 between them?

A

GC - 3

AT (U) - 2

5
Q

Why do H+ bonds between base pairs have a different bond lengths

A

because of the different structures of the bases

6
Q

which carbon of deoxyribose does the base attach, phosphate attach, and another nucleotide attach

A

base - carbon 1
Phosphate - carbon 5
another nucleotide - carbon 3

7
Q

When are the two cell cycle ‘check points’?

A

G1 - before S

G2- before M

8
Q

How does prokaryotic cell DNA replicate?

A

Initiation - Elongation - Termination of circular DNA

9
Q

Where are protease, lipase, amylase and ribonuclease secreted from?

A

Pancreas

10
Q

Whats pinicytosis

A

Liquid endocytosed

11
Q

Why would a cell have cytoplasmic extensions?

A

Move towards bacteria- phagocytose

12
Q

What is the direction of golgi processing

A

in - cis

out - trans

13
Q

What do glycogen inclusions look like on EM?

A

Small black speckled dots

14
Q

Where does replication of organelles occur in cell cycle?

A

G1

15
Q

What is the telomere repeating code?

A

TTAGGG

16
Q

Where is submetacentric centromere location?

A

Between acrocentric and metacentric

17
Q

What is it called where the spindle attaches to centromere in mitosis?

A

Kinetochore

18
Q

Where do the spindles arise from in the cell poles?

A

Pair of centrioles

19
Q

What are the spindles made of in mitosis?

A

Microtubules

20
Q

What are the phases of mitosis and what occurs?

A

Prophase: nuclear envelope disappears, mitotic spindles form, chromosomes begin to condense
Pro metaphase: chromosomes condense, spindles attach to centromere - kinetochore
Metaphase - line up at middle
Anaphase - centromeres divide, sister chromatids pulls apart to form 2 chromosomes at either pole by microtubules
Telophase: nuclear envelope reappears, chromosomes decondense, spindles disappear.
Cytokinesis- actin makes cleavage furrow, cytoplasm splits, 2 new cells

21
Q

What are chromosomal territories

A

Chromosomes have specific areas within the nucleus

22
Q

What is a pair of chromosomes that have the same genes one from maternal one from paternal? Is this more relevant for mitosis or meiosis?

A

Homologous e.g. of chromosome 1 (2 copies)

Meiosis as this is how they line up and split

23
Q

What are non-homologous chromosomes

A

chromosomes with different number e.g. one from chromosome 1 and one from chromosome 3

24
Q

If you paired a chromatid from the paternal chromosome 1 and a chromatid from the maternal chromosome 1 what would they be called?

A

Non- sister chromatids

25
Q

What process has 1 DNA replication 2 x cell divisions?

A

Meiosis

26
Q

Where does recombination (crossing over/chiasma) happen in meiosis?

A

Prophase I

27
Q

Where does random assortment occur in meiosis?

A

Metaphase I

28
Q

Does the nuclear envelope always reform in telophase of meiosis I?

A

Not always

29
Q

At end of meiosis I are the two cells haploid or diploid?

A

Haploid as 46 chromatids

30
Q

Does genetic diversity in gametes occur in meiosis I or II

A

I

31
Q

At the end of meiosis you end up with 23 chromosomes 23 single chromatids and 4 haploid daughter cells true or false

A

True

32
Q

What are two consequences of meiosis?

A

Maintaining equal number of chromosomes through generations and genetic diversity.

33
Q

Base pairs can be purine-purine true/false

A

false have to be a purine and a pyrimidine

34
Q

Name 2 covalent bonds in DNA double helix

A

Glycosidic and phosphodiester

35
Q

What is sugar+base+phosphate

compared to sugar+base?

A

nucleotide

nucleoside

36
Q

What is sugar+base+phosphate

compared to sugar+base?

A

nucleotide

nucleoside

37
Q

How can anticancer/antiviral drugs that target DNA get into the cell?

A

They are nucleotide analogues but without phosphate (so no -ve charge) so can get in cell. Once in they get phosphorylated and then can get incorporated into the DNA.

38
Q

What is the role of single-stranded binding proteins in DNA replication?

A

Prevents the helix rewinding - stabilises it

39
Q

What does DNA primase do? Does it act on both leading and lagging strand?

A

It adds an RNA primer to both leading and lagging strand for DNA polymerase to then replicate from.

It adds multiple to the lagging strand as need a new primase for each okazaki fragment thats made

40
Q

What are the 5 stages and 5 enzymes + 1 important protein involved in DNA replication?

A

1) Helicase/Topoisomerase
2) Single stranded binding proteins
3) Primase
4) Polymerase
5) Ligase

41
Q

What bonds does ligase reform? Give an example

A

Phosphodiester (back bone) that has been broken e.g. okazaki fragments back together in DNA replication.

42
Q

What is the structure of a nucleosome?

A

fragment of DNA wrapped around 8 histone proteins

43
Q

If making a cancer or virus drug that is a nucleoside analogue what part of the deoxyribose sugar would you alter so it prevents DNA replication?

A

Alter where DNA bonds would form, so drug could be incorporated and then prevent replication e.g. carbons 1, 3, OH on 5 on deoxyribose

44
Q

What does telomerase do?

A

Adds DNA repeats to 3’ end of telomeres, not in normal tissue but in embryos/gametes

45
Q

Two roles of telemeres

A

Prevent DNA damage/loss

Prevents fusion with other chromosomes

46
Q

Why isn’t DNA lost from the lagging strand in replication at the end?

A

Because of telomeres

47
Q

Two roles of nucleolus

A

That main function is the production of subunits which then together form ribosomes

Also 50% of RNA synthesis

48
Q

How is DNA polymerase stabilised on the strand to increase productivity of DNA replication?

A

Sliding clamp that encircles template strand and interacts with DNA polymerase to stabilise and enable high productivity of DNA replication.

49
Q

Slowing stalling or breakage during DNA replication is called what

A

DNA replication stress

50
Q

What is DNA replication stress

A

Inefficient replication that leads to slowing stalling or breaking during DNA replication

51
Q

Which 3 categories of problems can cause replication stress?

A
  • Problem with machinery of DNA replication e.g. helicase stalls
  • Problems on the DNA molecule, e.g. breaks, structure, RNA accidentally included
  • Problems with the response pathways
52
Q

What disease can be caused by slippage causing micro satellite DNA repeats

A

Huntingtons

53
Q

BRCA gene deficiency causes breast cancer by which DNA replication error leading to DNA replication stress

A

Error in DBS repair allowing DBSs to persist

54
Q

Give two examples of machinery errors leading to DNA replication stress

A

Helicase and Polymerase issues

55
Q

Give two examples of DNA problems that prevent replication fork progression.

A
  • Lesions
  • Secondary structures

Both these get in the way so prevent continuation of DNA replication

56
Q

Give two examples of fault DNA repair that prevent DNA replication continuing?

A

BER defects

DBS repair defects

57
Q

What kind of DNA replication error can cause nucleotide misincorporation (base mismatch)

A

Machinery defect - error in exonuclease function of DNA polymerase

58
Q

What is the difference between the exonuclease function of DNA polymerase and the DNA repair BER?

A

DNA polymerase only during S phase

BER throughout cell cycle

59
Q

What is damage to structure of DNA e.g. caused by UV damage called?

A

A lesion

60
Q

What are two consequences of DNA replication error?

A

Cancer/Cell death (ageing)