the nucleus Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

what is the nucleus surrounded by?

A

Surrounded by double membrane nuclear envelope, except for links to cytosol via nuclear pores.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what does the nucleus involve?

A

Involved in synthesis of mRNA, rRNA, tRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what does it house?

A

Houses the genetic material
membranous sac containing densely packed proteins & DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the structure of DNA

A

double helix and a chemically inert structure. and also contains 2 antiparallel strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what does antiparallel strands run

A

1 strand runs 5′ to 3′ while the other runs 3′ to 5′).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does purine and pyrimidine bases project

A

toward the axis of the helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the base pairs

A

A and T
C and G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what does adeine pair up with

A

purine adenine always pairs with pyramidine thymine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does prymidinae cystonie pair up with?

A

pyramdiine cytosine always pairs with purine guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the nucleoplasm?

A

proteins & DNA suspended in aqueous medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the nucleous?

A

region involved in ribosome synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how is the nuclear envelope formed

A

formed by 2 concentric membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are nuclear pores?

A

transport into and out of the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the nuclear localisation signal

A

short amino acid sequence that acts as a signal for the transport of proteins from the cytoplasm into the cell nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how is the the inner nuclear membrane formed?

A

formed by using Cytoskeletal nuclear lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

is the nucelous membrane bound?

A

NO

17
Q

what is the function of nucelous?

A

ribosome assembly

18
Q

what is the fibrillar centre?

A

(pale): contains inactive (not being transcribed) DNA

19
Q

what is the Dense fibrillar component

A

contains pre-rRNA molecules in the process of being transcribed from DNA templates

20
Q

what is the Granular component

A

contains mature ribosomes, ready for export into cytoplasm

21
Q

how does the ribsosmes get assemebled in the nucelous?

A

from rRNA molecules (transcribed from DNA template; pre-rRNA transcript processed by snRNA) & ribosomal proteins

22
Q

what does the greater size or complexity of an eukaryotic cell mean?

A

genomes means that elaborate mechanisms are needed for Packaging of DNA

23
Q

what is the role of chromatin?

A

DNA Packaging
DNA Replication and Repair
Regulation of Gene Expression

24
Q

what is heterochromatin? (dense)

A

found where there are few or no genes, or in gene-containing regions where the genes are inactive

25
Q

what is Euchromatin (less dense)

A

found where there are many active genes

26
Q

what is chromatin arranged as?

A

repeated units ‘Nucleosomes

27
Q

what is dna bound to?

A

bound to proteins called ‘Histones’ to form chromatin.

28
Q

why do we call it supercoiled DNA

A

if the axis of a double helix is coiled around itself we call it supercoiled

29
Q

why are supercoiled DNA called topoisomers?

A

genetically identical, but topologically different

30
Q

how is the DNA packaged?

A

1) naked DNA arranged into nucleosomes
2)nucleosomes are supercoiled in compact solenoid fibres
3)these fibres are arranged into loops attached to “chromosome scaffolding proteins)

31
Q

what is the exception we get to see chromosomes under a microscope?

A

as cell gets ready to divide chromosomes condense into short, ‘homologous pair’ dyad structures

32
Q

breifly explain what happens during mitosis and meiosis?

A

dissolution of the Nuclear Envelope
Chromosome dyads migrate (along cytoskeletal fibres) to opposite poles of a spindle within the nucleus.
nuclear envelope re-forms x2 around the 2 sets of separated chromosomes

33
Q

what does the nucelous envelope seperate?

A

separates the contents of the nucleus from the cytoplasm.

34
Q

nuclear pore and routes?

A

Nuclear pores are the only routes between the nucleus and cytoplasm.

35
Q

what is the nucelous involved in?

A

Transcription and processing of RNA
Ribosome assembly

36
Q
A