Module 6 Flashcards
What are the 5 essential characteristics of hereditary material?
- Localized to the nucleus
- stable
- sufficiently complex
- accurately replicates
- mutable
Who was DNA isolated by & when?
Friedrich Miescher, 1860s
What did Miescher isolate DNA from?
nuclei of white blood cells,
salmon sperm
What are the DNA base pairs?
T&A
C&G
Directionality of a single strand of DNA is
based on what?
the carbons of (deoxy)ribose
5’ end terminates
with _________ group?
3’ end terminates with a ____________
(-OH) group?
- phosphate group
- hydroxyl group
- when a new strand of nucleic acid (DNA
or RNA) is built, the direction is
always? - new nucleotides are added to which end?
5ʹ to 3ʹ
3ʹ end
How many bp makes a complete turn in a DNA double helix?
10bp
▪ 3.4 nm distance
two strands are antiparallel or parallel?
antiparallel
What 2 things hold DNA together?
▪ hydrogen bonding between
nitrogenous bases
▪ base-stacking/pi-stacking between
nucleotides
Short segments of what may help control gene expression?
H-DNA
What are the 4 important processes for the genome?
- Synthesis of RNA and cellular proteins
- Replication
- Segregation of chromosomes (cell division)
- Compaction: have to fit in a cell or nucleus of cell
- Which genome is usually 5 to 200 kilo base pairs (Kbp), packaged in chromosome?
- Bacterial genome how many bp and its shape?
- Viral genome
- few million bp (1–10Mbp, avg. 4Mbp),
circular, looped and supercoiled
- Eukaryotic genome: __ Mbp – >____Gbp, linear, in several chromosomes, coiled with histones, supercoiled and more
- Archaeal genome – 500Kbp–6Mbp, what is the shape?
- 5Mbp – >100Gbp,
- circular, coiled with histones
T or F As a general rule, larger genomes
have more genes
True
Viral chromosomes can come in what forms (3)?
- Double or single stranded RNA (ds or ssRNA)
- Double or single stranded DNA (ds or ssDNA)
- Circular or linear with single chromosome or a number of DNA molecules
which virus is enclosed in protein shell (capsid) and external membrane?
enveloped virus
what is a non-enveloped (naked) virus?
a virus enclosed only in protein shell
(capsid)
What is a retrovirus?
RNA viruses that contain a gene for reverse transcriptase in their genomes
T or F not all RNA viruses are retroviruses
(but all retroviruses are RNA viruses)
True
what is an example of an enveloped retrovirus?
HIV is an enveloped retrovirus
Haploid genomes often have smaller, circular pieces of autonomously replicating
DNA also known as?
plasmids
what is a Nucleoid
the dense non-membrane region where the chromosome is supercoiled
Bacterial chromosome condensation by proteins average loop contains how many kb of DNA
40 kb of DNA
What proteins form dimers
that hold coils of DNA?
SMC (structural maintenance of
chromosomes)
STARTT ABOVE HERE
Define tandem repeat
pattern of one or more nucleotides in repeated units directly adjacent to one another
VNTRs fall into which category of repetitive element?
A) tandem repeats
B) satellite DNA
C) retrotransposons
D) SINEs
E) telomere
A & B
What do euchromatin regions contain and how do they look in interphase?
actively expressed genes
and are less condensed during interphase
What do heterochromatin regions contain and how do they look in interphase?
fewer gene expressions, remain condensed
▪ variable levels of condensation
▪ related to levels of transcription of resident genes
Facultative or Constituitive?
facultative heterochromatin
Where is constitutive heterochromatin found?
Is it condensed?
What is it composed of?
centromeres & telomeres
permanently condensed
repetitive DNA sequences
What is the size of nucleosomes?
What is the core particle of a nucleosome?
- 10 nm fiber
- dsDNA wrapped around an
octamer of histone proteins
Label each step
300nm fiber and scaffold,
aka radial loops
tighten those loops!
Nucleosomes (10nm fiber)
30nm fiber
H1 histone on linker DNA
Step 1A: Nucleosomes (10nm fiber)
1B: 30nm fiber
2:H1 histone on linker DNA
3: 300nm fiber and scaffold,
aka radial loops
4: tighten those loops!
When does the 30 nm fiber form?
when the 10-nm fiber coils into a
solenoid structure
Interphase chromosomes have variably sized loops of 30-nm
fibers attached to what?
a non-histone protein chromosome scaffold
What forms the 300 nm fiber?
loops on the scaffold
Histone proteins are directly involved in
which levels of chromosome packaging in
eukaryotes? (select all that apply)
A) nucleosomes
B) 30nm fiber
C) 300nm fiber (radial loops)
D) 700 nm fiber
E) loop tightening
A & B
How can specific locations on chromosomes be visualized?
fluorescence in situ hybridization
(FISH)
Different stains and dyes are used to produce __________-______ _______ _________ on chromosomes.
broad-scale banding patterns
Which banding patterns are standard for human chromosomes?
G (Giemsa) banding;
What do archaeal chromosomes look like?
Genome size?
What % of archael genome sequences are protein coding? (similar to bacteria, greater than eukaryotes)
single, circular chromosome w extra-chromosomal plasmids
varies over more than a tenfold
87%
Repetitive sequences and intergenic regions are found where?
archaeal genomes
T/F Archaea have histone complexes as in eukaryotes.
TRUE
T or F DNA can only be negatively
supercoiled
False, DNA can be negatively or positively
supercoiled
which type of super coiling is more common between negative and positive anf why?
negative is more common because
The supercoiling process is controlled by which two main enzymes?
DNA gyrase/ topoisomerase II
Topoisomerase I
The DNA and associated proteins of a eukaryotic chromosomes are called ?
chromatin
Total amount of DNA varies substantially
amongst eukaryotes and may or may not be associated with what?
relationships or complexity of organism
Amoeba has almost 100 times more DNA than Homo sapiens, this is called?
C-value paradox
Number of genes is more closely associated with what than total number of base pairs (bp)?
complexity
T or F increase in gene number means
increase in organismal complexity
True
In the human genome, around _____% of the genome is repetitive, while about _____% is coding.
A) 60; 30
B) 50; 50
C) 30; 60
D) 60; 1-2
E) 1-2; 90
D) 60; 1-2
- The majority of repetitive DNA in the
human genome is found where? - LTR = ?
- in LTR and non-LTR retrotransposon sequences
- long terminal repeat
what carries coding sequence for reverse transcriptase (pol)?
retrotransposons
T or F LTRs (long terminal repeats) are a nonrepetitive sequence specifically flanking LTR retrotransposons
False, they are REPETiTIVE
LINEs and SINEs are ____-_____
retroelements that together make
up over 30% of the human genome
non-LTR retroelements
LINE = ?
SINE = ?
LINE = long interspersed nuclear element (several thousand bp long)
▪ SINE = short interspersed nuclear element (several hundred bp long)
