Cell structure + all cells arise from other cells Flashcards
function of the nucleus
site of DNA replication
contains genetic code for each cell
structure of the nucleus
-Nuclear envelope: double membrane
-nuclear pores : allows the passage of large molecules through
-nucleoplasm: granular jelly - like material making up the bulk of the nucleus.
-chromosomes : protein-bound linear DNA
-nucleolus : small spherical region within the nucleoplasm. manafactures ribosomal RNA and ribosome production
structure of mitochondria
-double membrane
-inner membrane : cristae
-fluid centre called mitochondrial matrix
-loop of mitochondria DNA
function of mitochondria
-Site of aerobic respiration
-site of ATP production
-its DNA codes for enzymes needed in respiration
structure of the chloroplasts
found in plants and algae
-surrounded by double membrane
- contains thylakoids
-fluid filled stroma contains enzymes for photosynthesis
functions of chloroplasts
-site of photosynthesis
structure of ER
RER
- contains a folded membrane called cisternae which increase SA.
-have ribosome attached on cisternae
SER
-contains a folded membrane called cisternae which increase SA
function of ER
RER:
-provides a large SA for the synthesis and transport of proteins
SER:
provides a large SA for the synthesis and transport of lipids and carbohydrates
functions of Golgi apparatus:
1) modified, packages and transports proteins: adds carbohydrates to make glycoproteins
2) modifies, packages and transports lipids; produces secretory enzymes
function of lysomes
- contains digestive enzymes : breaks down organelles for reuse of materials
- breaks down dead cells (autolysis)
-release enzymes to the outside of the cell to destroy material (exocytosis)
-hydrolysis phagocytic cells :
structure of ribosomes:
-80S - found in eukaryotic cells, larger ribosome (25nm)
-70s - smaller ribosomes found in prokaryotic cells , mitochondria and chloroplast
function of ribosomes
-site of protein synthesis
structure of cell wall
found in plants and algae
plants- made up of microfibrils of the cellulose polymer
-fungi - made of chitin- a nitrogen containing polysaccharide
-bacteria: murein
function of cell wall.
provide support + mechanical strength
function of vacuoles
-maintains cell structure
-acts as a temporary energy store ; cell sap is a solution containing sugars and amino acids
-pigment may colour petals to attract pollinator
Describe how prokaryotic cells are different from eukaryotic.
Smaller.
- Cytoplasm lacks membrane-bound organelles.
- Smaller ribosomes. (70s)
- No nucleus.
- A cell wall that contains murein.
why are viruses classified as non living
-they are acellular ( not made up of cells)
- no cytoplasm
-no metabolism
-cannot self replicate
describe the structure of viruses
- made up of nucleic acid: codes for protein
-capsid protects genetic material
-have attachment proteins: bind to the receptor .
how do viruses replicate?
-attachment proteins bind to receptors on host cells.
-virus injects its viral nucleic acid into the host cell.
-virus uses the host cell’s machinery and resources, such as enzymes and ribosomes, to replicate viral particles.
New viral particles are released from the host cell.
why is it so difficult to develop effective treatments against viruses?
-replicate inside living cells so difficult to kill them without killing the host cells.
when does DNA replication takes place
interphase stage
outline what happens during interphase
- G1) cell grows and protein synthesis
-S) DNA replicates –> chromosomes consists of two sister chromatids joined at centromere
G2) cell continues to grow + preperation for mitosis
what is mitosis ?
- a parent cell divides to form two daughter cells.
purpose of mitosis
-growth of multicelluar organisms
- cell replacement/ tissue repair
- asexual reproduction
