The Nucleus + DNA Packing Flashcards
The nuclear envelope consists of the following:
A double unit membrane
Perinucleur space
Which of the following statements is true?
Eukaryotic cells have a nucleus
What are the benefits of having a separate, membrane bound nucleus?
Enabled the evolution of SPLIT genes + alternative splicing
Rapid response to external environment
Separation of delicate DNA from cystoskeletal filaments
The nucleus may have evolved from membrane INVAGINATIONS which can be seen in modern bacteria. True or false?
True
What does DNA stand for?
deoxyribonucleic acid (DNA)
Name the process these molecules go through:
DNA, mRNA, Protein
replication, transcription, translation
What are the regulatory regions of genes known as?
Promoter / enhancer
What is true about prokaryotic GENES?
Prokaryotic genes are simultaneously transcribed + translated.
Prokaryotic genes are SPLIT into coding exons and NON- coding introns.
How many chromosomes do we have?
46
Humans have 2 sex chromosomes. What are these called?
X chromosome and Y chromosome
XX = female. XY = male.
What are our remaining chromosomes called?
autosomal chromosomes
What are the two arms of a chromosome called?
Short = P arm Long = Q arm
When is highest level of DNA packaging achieved?
Mitosis
DNA and associated proteins in nucleus form a material known as Chromatin.
True or false?
TRUE
What does this picture show?
Beads on a string
Nucleosomes
Which of the following HISTONES are found in nucleosome core?
H2A
H2B
H3
H4
Which of these describes the Nucleosome Core?
An Octamer
How much DNA is wound around the HISTONE core in the nucleosome?
146 nucleotides
Which ADDITIONAL protein is used to twist the Beads-on-a-String form of Chromatin into 30nm fibre?
H1
What structure are chromatin loops attached?
Nuclear Scaffold
What is active DNA and highly packaged SILENT DNA known as?
Active - Euchromatin
Silent - Heterochromatin
What is MAXIMUM level of DNA packaging possible?
10 000
Nuclear Envelope consists of 2 membranes (inner and outer) which meet at nuclear PORES.
True or false?
TRUE
Which type of cytoskeletal element support the nuclear envelope?
Intermediate filaments /
Nuclear Lamina
Label diagram of Nuclear Pore Complex
A ( squiggly things poking out top)
B ( green thing holding on)
C (blue squiggly things coming out bottom of opening)
A - Cytoplasmic Fibrils
B- Central ring / Transporter
C - Nuclear Basket
Nuclear pores regulate the flow of ALL molecules into OR out of nucleus.
True or false?
False
Nuclear Localisation Signals are REMOVED from proteins after they have been transported INTO nucleus.
True or false?
False
Nuclear import receptors are called… and export receptors are called…
Importins
Exportins
What statement about Nuclear Localisation Signals (NLSs) is FALSE?
NLSs are removed on entry of the protein into the nucleus.
Lopped domains are directly involved in…
Packaging Chromatin in chromosomes
Core nucleosomes consist of the following histones:
2 EACH of H2A, H2B, H3, H4
What fold level of packaging does the ‘beads-on-a-string’ form of CHROMATIN cause?
3
