Lecture 3 Flashcards
how many base pairs are in a genome?
3 billion
how does an offspring get its genome?
the offspring gets a set of genomes from each parent, one from the mother and the other from the father
does the size of a genome relate to how complex an organism is?
no
how many genes code for proteins?
20, 000
how much of the genome is repetitive DNA?
about half of the genome
how much of the genome codes for proteins?
about 1 percent
what are lines?
long interspersed nuclear segments
what are sines?
short interspersed nuclear segments
what happens to Retrotransposons?
get made into RNA during transcription
how do DNA-only transposons move through the genome?
through a DNA intermediate
what are protein-coding exons?
segments of DNA that are translated into proteins
what are simple repeats?
short segments of DNA that are repeated
what are segment duplications?
large duplicated DNA segments within the genome
what are unique sequences?
sequences within the genome that only occur once
what are the regions that get spliced out of mRNA called?
introns
how is DNA packaged in prokaryotes and why?
DNA is folded 1000 times to fit in the cell better
is genome packaging easier in prokaryotes or eukaryotes and why?
prokaryotes because eukaryotes are more complex
where is DNA held in the cell?
nucleus
does the nucleus in eukaryotic cells have a membrane?
yes
what is the job of Florence in Situ Hybridization?
technique to see certain DNA sequences within the cell
what is the chromosome solution?
eukaryotic genome is packaged into chromosomes
what do chromosomes consist of?
a long linear DNA molecule and chromatin
what is the process of Florence in Siti Hybridization?
a probe binds to a DNA sequence of interest and the probe has to hybridize to bind to the DNA. The probe gives off a fluorescent signal which allows researchers to see the DNA segment of interest
how many pairs of chromosomes are there?
23
how many chromosomes are there in total?
46
what is chromatin?
a complex of DNA and protein
what does it mean that chromatin is dynamic?
chromatin can change to become more accessible for transcription
what happens during the mitosis stage of cell division?
spindle fibres separate the chromosome pairs and put them at the edges of the cell. Then the cell divides
what happens in the interphase stage of the cell cycle?
DNA duplicates
what are the two main stages in the cell cycle?
interphase and mitosis
what happens to chromatins during interphase?
they isolate from cells
what is the fundamental unit of chromatins?
nucleosomes
what is decondensation?
a process researchers do to loosen DNA structure
what are histones?
small proteins rich in lysine and arginine
what is the job of histones?
use their positive charge to balance the negative charge in DNA
what are the four main proteins histones are main of?
H2A, H2B, H3 and H4
what does an octamer core consist of?
H2A, H2B, H3 and H4 a pair of each protein
what molecules form chromatin loops?
sequence-specific clamp proteins and cohesion
what is H1?
a linker histone
what replaces condensins when cells go through mitosis and why?
cohesins so the chromatin can loop and become more compact
how much shorter does the DNA molecule become when packaged into a chromosome?
it becomes 10, 000 times shorter
what molecules make changes in the chromatin structure?
Chromatin remodelling complexes and histone-modifying enzymes
what is heterochromatin?
highly condensed regions of chromosomes
what is the condensation like in chromatin?
constitutive always condensed or facultative condensed only in certain regions
what type of chromosomes does heterochromatin have?
meiotic and mitotic chromosomes
what region in the nucleus does heterochromatin lie?
in regions where gene expression is suppressed
what is euchromatin?
non-highly condensed chromatin
what is the degree of condensation like in euchromatin?
it varies
what is the level of activity like in euchromatin?
it varies
what region of the nucleus is euchromatin found in?
areas where genes can be expressed
which molecules modulate the
reversible switching from euchromatic to heterochromatic regions along chromosomes?
Localized covalent modification of histones, chromatin remodelling complexes, and RNA polymerase (transcription) complexes
what is chromosome painting?
a technique that uses fluorescent or radioactive probes to label and visualize specific regions in the genome
what chromosomes are found in the condensed chromosomal territory?
heterochromatin
Is DNA replication conservative or
semiconservative?
semiconservative
What is the direction of DNA
replication?
bidirectional growth starting from one point
Where does DNA replication start?
replication origin at the same location
which cells use bidirectional growth?
Eukaryotes and bacteria use this method
What are some of the characteristics of the sequences at replication origins?
-Easy to open
- A-T rich
-Recognized by initiator proteins that bind to the DNA
How many origins or replications do bacteria have?
one
how many origins or replications do eukaryotes have?
multiple
how does DNA replication proceed in bacteria?
circularly
what is the symmetry of the replication fork like?
asymmetrical
what are the ingredients for DNA synthesis? (6)
Origin of replication, primers, dNTPs, ATP (as an energy source), DNA polymerase, accessory proteins
