Lecture 1: Cells? Flashcards
(35 cards)
Prokaryote cell parts
- cytoplasm
- flagellum
- ribosomes
- nucleoid (DNA)
- plasma membrane
- cell wall
- capsule
- plasmid
- pili
Plant cell parts
- Rough ER
- Smooth ER
- Ribosomes
- central vacuole
- Tonoplast
- microfilaments
- Intermediate filaments
- microtubules
- chloroplasts
- plasmodesmata
- cell wall
- plasme membrane
- peroxisome
- mitochondria
- Golgi apparatus
- centrosome
- nucleus .. Chromatin, nucleolus, nuclear envelope
Animal cell parts
- Nucleus
- Nuclear envelope
- chromatin
- nucleolus
- glycosomes
- smooth ER
- cytosol
- mitochondrion
- centrioles
- centrosome matrix
- microvilli
- microfilament
- microtubule
- peroxisome
- secretion via exocytosis
- Golgi appaatus
- rough ER
- ribosomes
Centriole…
Organise spindle fibres in mitosis
Glycosome…
a peroxisome involved in glycogen storage & metabolism
Lysosome…
small vacuole
Eukaryotic cells are packed full of…
MEMBRANES. in 5ml of hepatocytes (teaspoonful) there are ~ 100m^2 of membranes
proteins in cells ____ of the volume of the cytosol
20-30%
Cytosol…
Aqueous component of the cytoplasm of the cell. Organelles & particles are suspended here
Why are cells so small?
- metabolism needs fuel from outside & produces waste products
- — exchange limited by surface area to volume ratios - smaller cells are easier to turn over/ replace
graph showing SA:V and side length of cube
shorter the side length of cube the higher the SA:V
Even small cells can have problems with SA for transports so…
in cells specialised for transport/exchanging materials, SA is dramatically increased and mitochondria abundant. E.g. microvilli in the intestine to absorb nutrients
Cell walls e.g. for root hair cells are…
all wiggly and folded = increased SA
a coenocytic structure =
multinucleate cells
some large cells do exist they often have…
a coenocytic structure with multiple nuclei and chloroplasts & a large vacuole
membranes allow,,,
compartmentation
why is compartmentation by membranes good?
- different environments (e.g. pH in vacuoles, mitochondria and cholorplasts)
- assists metabolic regulation by keeping enzymes, substrates and regulators separate
- locally high metabolite concentrations
- sequestration of toxic substances
- turnover of substances and organelles
- cells secrete and internalise large numbers of proteins -ER
Internal compartments of chloroplasts and mitochondria have an..
acidic pH to drive ATP synthesis
Nucleus contents:
genome, DNA replication, transcription, RNA processing, BUT translation is in the cytoplasm
Nucleus regulation:
Compartmenting the genome from the cytoplasm allows regulation of gene expression. (e.g. post-transcriptional processing, such as splicing (alternative)).
RNA splicing –>
RNA splicing is the process by which introns, regions of RNA that do not code for protein, are removed from the pre-mRNA and the remaining exons connected to re-form a single continuous molecule.
Nucleus Transport:
nuclear pore complexes transport RNA, ribosomes, proteins, carbohydrates, signalling molecules and lipids. Small particles (
Cytoskeleton:
- protein filaments and motor proteins
- protein filmanets form a 3D mesh -> rigidity, shape & structure
- movement (trackways)
In muscle cells, _____, comprises 10% of total cell protein, even in non muscle cells ___ forms 1-5% of cellular proteins
actin
