Genetics Flashcards
What are Eukaryotic cells?
Membrane bound organelle, can be unicellular or multicellular
What are Prokaryotic cells?
Are not membrane-bound, are always part of unicellular organisms
What is an example of a cell that has no nuceli?
Red blood cells
What is an example of a cell that has more than one nucleus?
Skeletal muscle cells and liver cells
Describe the components of the nuclear envelope
Inner and outer membrane made of phospholipid bilayers.
Outer membrane has lots of anchoring proteins that allow it to stay suspended in cytoplasm
Inner membrane is covered by nuclear Lamina (network of Lamin proteins, creating a dense protein web for chromatin to drape over)
Large nuclear pores create the nuclear pore complex lines with nucleoproteins (basketball hoop)
Describe the function of the nuclear envelope
selectively permeable, large like nucleic acids and proteins cannot get through but small water molecules can
What is chromatin? Describe the different types
helps pack all the DNA, made of 46 separate DNA molecules, each of which is called a chromosome
Euchromatin: loosely packed and frequently transcribes and translates DNA to mRNA for things that are used often
Heterochromatin: densely packed and only rarely transcribed and translates
What are histones and what is their role?
They help control DNA and in the case they are a methyl group it prevents DNA from getting transcribes. DNA is tightly packed around 8 histones
What is a nucleosome?
double helix DNA wrapped twice around 8 histones
What is rDNA and where does it originate?
Special kind of DNA that can be transcribed into rRNA which is folded around some proteins inside the nucleoulus to create a ribosome which then passes through the nuclear pore
What does a ribosome do?
Converts mRNA into a string of amino acids through translation
Once proteins are made during translation where do they go?
endoplasmic reticulum
Describe the process of transcription (10 steps)
Two strands of DNA: coding strand and template strand
1. promoter region marks starting point
2. proteins and enzymes come together to form pre-initiation complex around promoter
3. Elongation, RNA polymerase shears hydrogen bonds unzipping the nucleotides
4. RNA polymerase follows template strand to assemble mRNA molecule
5. mRNA is different in that it replaces Thymine with Uracil and runs in the opposite direction
6. as the RNA polymerase moves down the DNA the hydrogen bonds reform
7. RNA polymerase reaches terminator sequence creating a hairpin loop which detaches
8. 7-methylguanosine cap is added at the 5’ end and a poly-adenine tail of polyadenylate polymerase (enzyme) is added at the 3’end
9. Introns are cut out of the sequence by a splicesome
10. floats out of the nucleus and meets up with ribosome in cytoplasm
Describe the process of translation (7 steps)
- Ribosome grabs mRNA (initiation)
- Each 3 letters are codons (either an amino acid, or a start/stop codon). Start codon is found in ribosome
- tRNA takes amino acids to ribosome (short RNA sequence for finding specific amino acid)
- briefly binds to corresponding mRNA in the A site before moving to P site
- peptide bonds hold proteins together between A and P site as the strand tails on the E side (polypeptide tail)
- stop code is found and protein producing stops
- the newly formed protein is carried to endoplasmic reticulum where it undergoes further preparation
