Lecture 5&6 - Cell Structure & Function Flashcards
What is the most prominent structure in eukaryotic cells?
Nucleus
Where is rRNA synthesised, precisely
Nucleolous
What is the role of the nuclear pores?
allow exchange of material between the nucleus and cytoplasm
What is chromatin?
Uncondensed form of DNA associated with histone proteins (in eukaryotes) and contains some RNA
how many layers of phospholipids does the nuclear membrane have?
4 (2 bilayers) It is a double membrane
What is the nuclear pores lined up with?
a complex of 8 proteins
What is the analog of cytoplasm in the nucleus?
Nucleoplasm
What is the function of genes?
Small sections of DNA that usually code for proteins, sometimes RNA(rRNA)
What is the unit of heredity?
genes
What are the differences in the structure of free and bound ribosomes?
there is no difference in structure
What is the function of free ribosomes?
make proteins that function in the cell (work Intracellularly) Eg; enzymes that catalyze first steps of sugar breakdown
what is the relation between protein synthesis and ribosomal count?
directly proportional
What are the structural differences between ER and Golgi body?
- ER is continuous with nucleus, Golgi body is NOT
- ER are physically connected, Golgi body has separate stacks of 3-20 cisternae (both Have cisternae)
Describe the steps of protein synthesis
- mRNA is synthesised from DNA in the nucleus
- mRNA exits via nuclear pores to the ribosome
- at ribosome mRNA contains the code to make proteins while tRNA comes to the ribosome with the amino acid corresponding to the codon (triplet)-
- polypeptide chain stops building when STOP codon is reached
describe the steps of ribosomal synthesis
- rRNA is synthesised in the nucleolous using DNA
- Combine with protein molecules imported from cytoplasm, now exist as subunits
- small and large subunits exit the nucleus via nuclear pores
- Small and large subunits combine in the cytoplasm