(3) Cell structure Flashcards
what is the ultrastructure of the cell
the internal structure of each cell type that suits it for its job
what is a eukaryotic cell
plant/ animal cell with a distinct nucleus and membrane bounded organelles
what is a prokaryotic cell
bacterial cell
no nucleus
what is the general structure of the nucleus
spherical double membrane (nuclear envelope) nuclear pores at least one nucleolus between 10-so micrometers in diameter
what is the nuclear envelope
a double membrane that surrounds the nucleus. the outer membrane is continuous with the ER and often has ribosomes on its surface
controls entry and exit of materials in and out of the nucleus
what are nuclear pores
allow the passage of large molecules such as mRNA out of the nucleus. around 3000 pores in each nucleus each 40-100 nm in diameter
what is the nucleoplasm
granular, jelly like material that makes up the bulk of the nucleus
what are chromosomes
where genetic information is stored as protein-bound, linear DNA
what is the nucleolus
small spherical region within the nucleoplasm
manufactures ribosomal RNA and assembled the ribosomes
what are the functions of the nucleus
manufacture ribosomal RNA and ribosomes
retain generic material of the cell in the form of DNA and chromosomes
act as the control centre of the cell through the production of mRNA and tRNA and hence protein synthesis
what is the role of the double membrane
controls the entry and exit of material. the inner membrane is folded to form extensions known as cristae
what are cristae
extensions of the inner membrane
provide a large SA for the attachment of enzymes and other proteins involved in respiration
what is the matrix in a mitochondria
contains proteins, lipids, ribosomes and DNA that allows the mitochondria to control the production of some of their own proteins
where are most enzymes for respiration found
the matrix of a mitochondria
what do mitochondria produce
ATP (the energy carrier molecule)
why do epithelial cells in the intestine have a lot of mitochondria
because mitochondria produce ATP which releases energy and epithelial cells in the intestine need a lot of ATP in the process of absorbing substances from the intestines via active transport
what is the chloroplast envelope
double plasma membrane surrounding the organelle that is highly selective in what it allows to enter and exit
what is the grana of a chloroplast
location of light absorption (first stage of photosynthesis)
stacks of up to 100 disc like structures called thylakoids which contain chlorophyll
what is the stroma of a chloroplast
a fluid filled matrix containing starch grains. The location of the 2nd stage of photosynthesis ( synthesis of sugar)
how are chloroplasts adapted for their function (3 ways)
1) granal membranes provide large SA for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis
2) fluid in the stroma possess all the enzymes needed to make sugars in the second stage of photosynthesis
3) chloroplasts contain both dna and ribosomes so they can quickly and easily manufacture some of the proteins needed for photsynthesis
what is the structure of the rough endoplasmic reticulum
tubules and flattened sacs surrounded by double membrane covered in ribosomes
continuous with outer nuclear membrane
what is the function of the rough endoplasmic reticulum
protein and glycoprotein synthesis (large SA)
provides a pathway for the transport of materials, especially proteins, throughout the cell
what is the structure of the smooth endoplasmic reticulum
more tubular appearance than RER.
tubules surrounded by a double membrane and no ribosomes on surface
what is the function of the smooth endoplasmic reticulum
synthesises, stores and transports lipids and carbohydrates