PP6 Flashcards
Explain the upper limit and lower limit of the size range of cells.
lower limit cannot be smaller then the collective size of the components required for life (aka DNA, ribosomes, etc)
Upper limit is imposed by the surface to volume ratio. As a cell increases in size, its volume grows proportionally more than its surface area.
Internal organization of bacteria and archaea
- they do not have internal membrane (like eukaryotes)
- They contain ribosomes (involved in making proteins), but are not membrane bounded.
- Have nucleoids (nucleic regions), which is where the DNA is located, which is set aside in a room with no real separation.
- May have plasmids, which are small circular molecules of DNA that carry a small number of genes.
Internal organization of animal cell
- like eukaryotes, has a nucleus
- like all eukaryotes, has membrane bounded organelles
- like all cells, has a plasma membrane
- like all cells, has mitochondria
- performs cellular respiration
- has chloroplast!
Internal organization of plant cell
- like eukaryotes, has a nucleous
- like all eukaryotes, has membrane bounded organelles
- like all cells, has a plasma membrane
- like SOME cells, has a cell wall (made of cellulose)
- has a large central vacuole which contains water and dissolved solutes, which provides flavour or compounds that can be toxic
- has chloroplast which performs photosynthesis
- has mitochondria which performs respiration, produces a usable form of ATP from carbohydrates form by the plant during photosynthesis
What is the cytosol? What else can it be called?
Also known as the cytoplasmic matrix is the liquid found inside cells. Its like the brought of a soup.
what is the cytoplasm?
its the area within the plasma membrane, which comprises of the cytosol, mitochondria, plastids, and other organelles (but not their internal fluids and structures), but not the nucleus.
**like vegetable soup: cytosol is the broth, organelles are the vegetables.
What is the endomembrane system? How doe they communicate? What does it include?
- organelles inside the cell that are not distinct
- they communicate with each other by membrane “bridges” or by the budding of vesicles (small membrane enclosed sacks)
- it includes: nuclear envelope, endoplasmic reticulum, Golgi apparatus, plasma membrane, vacuoles and vesicles.
What is the function of the nucleus and nuclear envelope?
Nucleus: contains DNA
Nuclear envelope:
- defines the boundary of the cell
- consists of 2 membranes (inner and outer) each is a lipid bilayer with associated proteins
What is the function of nuclear pores and nucleolus?
Nucelar pores: act as gateways allowing molecules to enter and and leave the nucleous
Nucleolus:
- site where rRna is synthesized.
- assembly site of large and small ribosomal subunits
What is the function of a ribosome? Free ribosome? Bound ribosome?
- complexes made of rRNA and proteins (forming large and small subunits)
- sites of protein synthesis, in which amino acids are assembled into polypeptides
Free ribosomes: found floating in cytosol, synthesize proteins that do not leave the inside of the cell
Bound ribosome: attached to the endoplasmic reticulum membrane, synthesize proteins that are secreted or are components of the plasma membrane
What is the function of the rough ER and smooth ER?
Rough:
- studded with ribosomes on the surface of the membrane
- synthesis of proteins can be secreted
- synthesis of membrane bound proteins
Smooth:
- outer surface lacks ribosomes
- functions in diverse metabolic processes, which varies with cell type
- synthesis of lipids, metabolism of carbohydrates, detoification of drugs and poison, storage of calcium ions
What is the function of the Golgi apparatus?
- looks like a series of flattened membrane sacks, called cisternal, a bit like the hole in a jelly filled donut.
- stacked cisternae bud to produce vesicles carrying processed proteins
- not physically continuous with the E.R.
- next stop for most vesicles budding from the E.R
Has 3 primary roles:
- further modifies the proteins and lipids produced by the ER
- cast as a sorting system for proteins going to their final destination
- synthesis of carbohydrates
What is the function of lysosomes?
- specialized vesicles coming from the Golgi
- responsible for intracellular digestion: degrade damaged or unneeded macromolecules (e.g., proteins, nucleic acids, lipids, complex carbs), bacteria or other smaller organisms that have been engulfed
- protons pump in the membrane, keeping the internal envirmnent at an acidic pH at around 5 (optimal pH for the degrading enzymes) by actively transporting protons (H+) into the lysosome.
What is the function of vacuoles?
- large vesicles derived from the endoplasmic reticulum and Golgi apparatus
There are 3 types:
- Food vacuoles in certain animal cells and single celled organisms formed by phagocytosis (phago = eating, cyto = cell). White blood cells eat bacteria, enclose them in a vacuole which fuses with a lysosome. Amoeba feeding.
- Contractile vacuole which excretes excess water in single celled organisms
- Central vacuole found in plant cells which stores water an dissolved substances. It exerts pressure on the cell wall to maintain cell shape
What is the function of the mitochondria? Mitochondrial matrix contains what?
- not part of the end-membrane system
- its a site for cellular respiration: metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats and other fuels
- Some cells have a a single large mitochondrion, more often a cell has hundreds to thousands of mitochondria (dependent on cell’s function)
- Enclosed by two membranes; outer membrane is smooth, inner membrane is convoluted, with infoldings called cristae
Inner membrane divides mitochondrion into:
- Inner membrane space: narrow region between inner and outer membrane.
- Mitochondrial matrix: contains enzymes, mitochondrial DNA, and ribosomes.
- Inner membrane is where cellular respiration takes place.
