Week 1 tute - biomedical basics Flashcards
DNA is ?% mass of a nucleus?
<20%
where are nucleoproteins synthesised?
cytoplasm
once sythesised, where are nucleoproteins transported into?
the nucleus
what are the 2 classifications of nucleoprotein
- histone proteins
- non-histone protein:
what is the purpose of histone proteins?
bind to DNA & control coiling of strand
what are the two types of non-histone proteins in the nucleus?
non-histone protein:
- enzymes for DNA & RNA synthesis
- regulatory proteins
what are the main types of RNA that can be found in the nucleus?
newly synthesised m-RNA, t-RNA & r-RNA
describe the structure of the nuclear envelope
2 lipid bilayers with intermembranous space, contains pores
what is the outer membranes of the nuclear envelope continous with?
ER (+ has ribosomes)
what is the purpose of the pores in the nuclear membrane?
permit & regulate (active) exchange of metabolites, macromolecules & ribosomal subunits between nucleus & cytoplasm
In dividing cells, chromatin appears in form of ______
chromosomes
In non-dividing cells, chromatin exists in 3 forms, they are:
- H?
- E?
- N?
- Heterochromatin-electron dense areas, of tightly coiled inactive chromatin
- Euchromatin-pale staining areas of DNA, active in synthesising RNA (e.g. m-RNA)
- Nucleolus:
•one or more in active cells
• site of r-RNA synthesis & ribosome assembly
what is heterochromatin?
electron dense areas, of tightly coiled inactive chromatin
what is euchromatin?
pale staining areas of DNA, active in synthesising RNA (e.g. m-RNA)
what is the nucleolus?
site of r-RNA synthesis & ribosome assembly, there are one or more within active cells
what is the difference in the appearance of the nucleus between inactive and highly active cells?
- inactive cells have small nuclei, condensed (hetero) chromatin, small or absent nucleoli
- highly active cells have dispersed (pale staining) chromatin (euchromatin) with prominent nucleoli
role of mRNA?
transcribes DNA instructions for protein synthesis & carries to cytoplasm
role of rRNA?
moves to cytoplasm becomes site of protein synthesis, it translates mRNA sequence into sequence of amino acids
role of tRNA?
transfers amino acids in sequence, from pool in cytoplasm, to elongating polypeptide chain being assembled
the cytosol (fluid matrix) colloidal solution contains? (list 6 things)
– water
– electrolytes
– suspended proteins
– neutral fats
– glycogen
– pigments
at what region in the nucleus are ribosomes assembled at?
the nucleolar region within nucleus
where does the synthesis of extracellular proteins occur? (e.g. digestive enzymes, some hormones, neurotransmitters)
Rough endoplasmic reticulum
what synthesises proteins to be used within the cell?
free ribosomes in the cytoplasm
describe the structure of the ER
a system of paired membranes with matrix (fluid-filled space), cisternae (flattened sacs) & vesicles connecting parts of inner cell
what is the matrix of the ER continuous with?
- cell membrane
- space between 2 layers of nuclear membrane
- other membranous organelles
the ER functions as tubular __________ _________ for transport of molecules through cell
the ER functions as tubular communication network for transport of molecules through cell
the ER’s large surface area & attached multiple ________ ______ means it has an active role in ___ ______
the ER’s large surface area & attached multiple enzyme systems means it has an active role in cell metabolism
where is the main site of structural modification for the following enzymes?
–pancreatic digestive enzymes
–liver plasma proteins
–lysosomal enzymes (all cells)
RER