NOTES - Week 2 - nucleus, mitochondria, chromosomes, structure of chromatin. Flashcards
EJ KLAR
Conclusion you can draw from these pictures.
Shows the big size of the nucleus in a cell and from the right we can see that vast majority of nucleic acids are in the nucleus. DAPI able to bind with nucleic acids region that is rich with Adenine and Thynine- thats why we see nucleic acids!
Explain the nucleus
It is what?
It can be said that it is what? And why?
What molecules does it contain?
What do you know about the amount of nucleus in a cell? Examples?
Most prominent membrane-bounded organelle.
“Controlling center of the cell” dvs contain nessecary info for survival and normal function of the cell.
Contains linear DNA molecules
Few cells that don’t have nucleus → highly specialised cells = RBC with only goal is to transport oxygen.
Also some have multiple nucleus.
Nucleus: generally important in cells because of function but not necessary for survival → means that stem cells need to have….
Explain the picture
Hints: what can you see, understand the arrows,
Electromicroscopy of nucleus
Clearly see membrane-bounded organelle.
On zoom in we can see pore complexes on aoom membranebounded organelle.
Name all the red parts
Explain the red box name that is bounded with the yellow net. What it is.
Tell me about the nuclear envelpope, what it is and what it contains. Also its functions.
Outer membrane: continuation of rough ER
Perinuclear space: between inner and outer membrane. Cont. of rough ER lumen
Lamina - specifik protein
Nuclear envelope function: physically separates nucleus from cytoplasma in Eukaryotes cells.
Functionally: separates 2 processes..
1. Copy of info (mRNA synthesis) from
2. Protein synthesis (occurs in cytoplasma/membrane of Rough ER)
obs separated by time and space
Outer nuclear membrane
Inner nuclear membrane
Perinuclear space
Size difference
OM and IM. Same by structure and thickness. Small differences. 7-8 nm thick
PS: 10-30 nm wide
Not a question - just look at the image and point out the things you know
What is NPC?
What does it consist of?
Large complicated protein complex which forms a channel - transport pathway.
Consists of proteins called nucleoporins (NUPS aka noobs) = involed in selecting molecules that are passing trough.
NPC responsible for protected exchange of components between nucleus and cytoplasma.
NPC density depends on function.
Schematic repr. of NPC
8 groups of Nups = spokes
What does the central transporter do?
It’s surrounded by..?
What assists the active transport macromolecules have.
- tell me more about what they do
What binds importing molecules and what binds exporting molecules.
Explain LINC
Nuclear lamina
2 types of lamina
Isoforms meaning
same gene but by changing parts - acquire different isoforms
What does nuclear lamina form
hint: appearance
What is lamina involved in?
What are laminopathies?
What is phenotypes
Different changes to the protein coding genes will lead to different disorder phenotypes. All linked with disfunction of lamina and LINC both protein complexes.
What is the nucleoplasm
What are non-histone proteins
What are histones?
Contains:
Contribute to?
What form
Aminoacids makes it postive
H1 DNA linkers-
Hjäölper att ske transkription även om dem är så tajta
Fill in red boxes
Majority of DNA is packed where?
What are nucleosomes
Histone octamere wrap around?
Linker DNA?
Chromatosome?
Chromatin är histoner packat runt DNA
nucelosome- packed twice
Name all parts of the picture
What is this structure called
Chromatin fiber
Explain this picture
The chromatin fibers forms a kind of loops. The loops are held together by red lines (scaffold proteins)
Scaffold proteins give structure to chromatin. By these loops = spiral structure
From DNA to metaphase chromosome?
8 steps (general understanding of order)
- DNA simplest level of chromatin
-
Nucleosome
DNA bound with histones ( + - charge) - Nucleosome 8 histones, 1,65x wraps around
- Chromatosome: nucleosome + H1 histone
- 30nm fiber
- loops avg 300 nm
- Compressed
- supertight coiling
What is Chromatin?
What is TAD and chromosomal territories?
State of euchromatin and heterochromatin in interphase!!!!
Topologically Association Domains (TADs):
▪ chromatine in further organized into TADs,
▪ regions within which DNA interactions are more frequent than with regions outside the TAD
▪ these domains facilitate regulatory elements, like enhancers, to interact more easily with their target gene
▪ each chromosome is divided into TADs
▪ TADs with repressed transcriptional activity tend to be associated with nuclear lamina, while active TADs tend to reside more in in the nuclear interior
Repressed = heterochromatin
Active tads = euchromatin
INTERPHASE CHROMATIN!!!!!!!!!!!!!
Eurochromatin
Heterochromatin
Difference?
More details about heterochromatin
Heterochromatin consist of constitutive heterochromatin and facultative heterochromatin:
Constitutive heterochromatin
- contains highly repetitive sequences of genetically inactive DNA (satellite DNA). Serves as a structural element of the chromosome.
In humans, chromosomes abundant with heterochromatic regions are chromosomes 1, 9, 16, 19, and Y chromosome.
It is stable during all stages of development in all tissues.
Facultative heterochromatin - the chromatin which become heterochromatic in certain cells and tissues e.g., it makes up the inactive X chromosome in female somatic cells (Barr body).
Facultative heterochromatin is reversible - may at time lose its condensed state and become transcriptional active.
Use the words methylated,
hypo-acetylated, and genetic recombination in context of this lecture
Functions of heterochromatin
- Centromere function
- Organisation of nuclear domains
- Gene repression (epigenetic replication)
Metephase chromosome
1/2
Metaphase chromosome
The tight coiling of the 250 nm fibre produces the chromatid of a chromosome.
■During the S phase (interphase) of the cell cycle replication of DNA take place and two identical chromatids are produced.
■Chromosomes (metaphase chromosomes mitotic chromosomes) can be observed during the cell division.
2/2
Fill in the gaps and explain what they are.
What are sister chromatides
What is Centromere
What is Kinotochore
And what it is needed for,
What is Satelittes
What is Secondary constriction?
Name all the different parts of the chromosome!
Think of association
What is NOR
The ends of linear DNA
(((it contains what repeated nucleotide sequence))))
Explain this
Represents structure of the telomeres.
6 nucleotide repetition will go (full varv)
T-loop
Functions of telomeres
What is ICFS? Short about symptoms?
Explain Molecular mechanism ICFS
Immunodeficiency – centromeric instability – Facial anomalies syndrome (ICF)
Symtoms in name!
What does she say in this slide?
Karyotype pictures: strange shape of chromosome - with stretched centromeric parts of it
= result of un/low methylated centromerc regions of chromosome
During cell division - this strange shape with centromeres in between
Set of chromosomes
Number, size and shapes of the metaphase chromosomes constitute the karyotype, which is distinctive for each species
(not important) A common misconception about humans and amount of chromosomes we have compared to our intelligence
Numbers characteristics for each species karyotype, not the size of the genome = not intelligence
Describe the human karyotype
Somatic and germ cells have..
What determines sex linked characteristics
What are the short regions of homology between the X and Y chromosome
What type of chromosomes are we talking about?
Sex chromosomes, but not all regions are sex-linked regions. They are called PS… because they behave in a ….
(Look at the pic)
Compare male and female chromosomes
What to extract for info from this picture
Schematic repr. of how barr body looks like
Microscopic slide (stain with specific dye) → barr body is dot
One chromosome heterochromatic → darker in microscope
OBS not normal karyotype
- Usually only 1 chromosome will be randomly staying active and all the rest will be inactivated
45, 0
turner syndrom. Deletion of x chromosomes. no barrbodies visible.
46, 0
male, only 1 x chromosome = no barr bodies visible.
Be able to undestand this image!
What conclusion can be drawn for this picture
Short list of chromosome groups by size. A largest. G smallest
Description based on position of centromere
The nucleolus
What exists here?
structure?
Prokaryotic chromosome
What is nucleoid
Nucleoid is a place in prokaryotic cells where most of the genetic information is stored
Size difference between stretched DNA of prokary. and cell
What helps maintain the nucleoid structure
What can be seen of these 2 pictures
Left:
Schematic rep. chromosome is already supercoiled and (+ binding proteins) will bend DNA to fit into the cell
Right: electromicroscopy, see the areas that rep. DNA chromosome supercoiled binded together with enzymes (who takes part in formation of nucleoid and enzymes which are involved in gene expression of the DNA)
Mitochondria
7.30 lecture 2 part 3
Cristae and matrix location?
Mitochondria and chloroplasts likely evolved from engulfed prokaryotes that once lived as independent organisms. At some point, a eukaryotic cell engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host eukaryote, gradually developing into a mitochondrion.
Self replecating means that it can replicate independently from cell cycle
mitochrondria has lot of similiarities with prokaryotes.
What is mitochondria composed of?
What is mtDNA
Features and functions of mitochondria
Summary lecture 2
obs more in answer
