Cells - Structure and Function Flashcards
1
Q
cell theory
A
- all life is composed of one or more cells
- cell = basic unit of life
- all cells come from other cells
2
Q
prokaryotic cells + 2 types
A
- no nucleus (nucleoid - SSC) or membrane-bound organelles
- make up unicellular organisms
- divide by binary fission
- 2 types: bacteria and archaea (extremophiles)
3
Q
eukaryotic cells + e.g.s
A
- nucleus, membrane-bound organelles, plasma membrane, cytoskeleton
- generally make up multicellular organisms
- animals, plants, fungi, protists (unicellular)
4
Q
why are cells small?
A
- small = increased SA:V ratio = increased efficiency of diffusion etc.
5
Q
what is a tissue and what are the 4 types?
A
- cells working together to perform a similar function + ECM - aqueous CHO + protein
- epithelial, connective, muscular, nervous
6
Q
4 levels of organisation
A
- Cell: smallest unit of living things, building blocks, vary in shape, size, function (specialised)
- Tissue: large numbers of the same type of cell
- Organ: made of at least 2 tissue types that performs a specific function within the body
- Organism: organs that work together to accomplish a common purpose
7
Q
cytoplasm vs cytosol
A
- cytosol = gel-like, fluid part of cell where most chemical reactions occur
- cytoplasm = cytosol + cytoskeleton + organelles (except nucleus)
8
Q
what is an inclusion?
A
- anything else in the cell not an organelle
- e.g. deposit of CHO, lipids, protein etc (may or may not be membrane-bound)
9
Q
structure and function of nucleus
A
- S = nuclear envelope (double membrane with pores)
- chromatin (DNA and proteins which make up chromosomes)
- nucleolus (formation of rRNA)
- F = control cellular functions by coding for proteins as well as cell division
10
Q
anuclear and polynuclear cell e.g.s
A
- anuclear = RBCs, daughter cells resulting from incorrect cell division, keratinocytes, lens fibres, platelets (cell fragments)
- polynuclear = skeletal and cardiac muscle fibres, daughter cells resulting from incorrect cell division
11
Q
structure and function of mitochondrion
A
- S = double membrane-bound organelle, inner membrane folds to form cristae and matrix inside
- F = site of ATP synthesis via oxidative phosphorylation to provide energy for the cell (occur more in cells w higher demands e.g. sperm + skeletal muscle)
12
Q
endosymbiotic theory + evidence
A
- mitochondria + chloroplasts derived from bacteria
- evidence e.g. own genome (mtDNA), double membrane
13
Q
structure and function of ribosomes
A
- S = not membrane-bound so not considered organelles, found ‘free’ or bound to RER, small and large subunit
- F = site of protein synthesis (proteins for use within cell are synthesised on free ribosomes whereas proteins destined for exocytosis are synthesised by ribosomes on RER)
14
Q
structure and function of RER
A
- S = abundant in cells specialised for protein secretion (b/c ribosomes), composed of flat cisternae studded w/ ribosomes, continuous w/ nuclear membrane
- F = folding and transport of polypeptides into transport vesicles
15
Q
protein production pathway
A
nucleus > ribosome > RER > transport vesicle > Golgi > secretory vesicle
16
Q
structure and function of SER
A
- S = 3D network of tubular structures continuous w/ RER - abundant in liver cells for detox
- F = synthesis of lipids and steroids as well as metabolism of CHO
17
Q
structure and function of Golgi apparatus
A
- S = flattened, membranous sacs (cisternae) in a parallel arrangement (full of enzymes)
- F = FMAP of proteins into secretory vesicles
18
Q
structure and function of lysosomes
A
- S = membranous sac of hydrolytic enzymes, made in RER and transported to Golgi > type of vesicle
- F = digest substances no longer needed in cell
19
Q
structure and function of secretory vesicles
A
- S = membranous sac produced by Golgi
- F = store proteins until their release from cell and assist in their transport out of the cell (if relevant)
20
Q
structure and function of plasma membrane
A
- S = phospholipid bilayer (separate internal and external) including cholesterol (rigidity b/c disrupts fluidity), proteins (communication and support) and CHO (recognition)
- F = regulate inputs and outputs of cell, communication, interface between intra and extracellular environment
21
Q
structure of phospholipid bilayer
A
- polar (hydrophilic) head on outside
- non-polar (hydrophobic) tail on inside
- allows water, lipid-soluble molecules and small molecules e.g. O2 and CO2 through (selectively permeable) - from high to low conc
22
Q
why can we ‘see’ plasma membranes under a light microscope?
A
- usually not visible to light microscope, only electron
- however glycoproteins and glycolipids are embedded in the membrane and can be seen under the light microscope
23
Q
function of proteins in the plasma membrane
A
- transport molecules across the membrane
- enzymes which catalyse reactions at the membrane
- provide links b/n membrane and cytoskeleton, ECM and adjacent cells
- receptors for receiving and transducing chemical signals
24
Q
function of carbohydrates in the plasma membrane
A
- most extrinsic proteins form glycoproteins, there are significantly more glycoproteins than glycolipids (only on outside of cell)
- F = cell-cell and cell-matrix recognition
25
Q
general features of bilayer membranes
A
- asymmetrical: outer and inner layers are not the same (diff chains/biomacromolecules attached)
- dynamic and fluid: lipids and proteins can move freely whereas monolayers have very little movement
26
Q
structure and functions of cytoskeleton
A
- S = internal scaffold of special proteins made up of microtubules, microfilaments (actin filaments), intermediate filaments
- F = movement of organelles within cell, maintaining shape of cell, cell movement (inc contraction), other specialised cell functions e.g. mitotic spindle
27
Q
structure and functions of microtubules
A
- S = spiral ring of 13 subunits which can rapidly polymerise and depolymerise
- F = give cell shape
- control transport of substances in and out of cell
- mitosis - formation of centrioles and spindle
- component of cilia and flagella of sperm
28
Q
examples of motile cilia and non-motile stereocilia
A
- motile (cilia): trachea and fallopian tubes (help transport/sweep) - 9 + 2
- non-motile (stereocilia): most other cells (stick up internally into plasma membrane and protrude out to form hair-like projections) - 9 + 0
29
Q
microtubule structure of cilia, flagella and centrioles
A
- motile cilia: 9 + 2 pattern (9 pairs of microtubules with 2 singlets in the middle) axoneme structure
- non-motile stereocilia - 9 + 0
- flagella: 9 + 2 (basal body is triplet)
- centrioles: 9 microtubule triplets in a pinwheel arrangement which helps arrange microtubules which move chromosomes during mitosis. centrioles are found in pairs at right angles to each other and are depolymerised/broken down after mitosis
30
Q
structure and function of actin
A
- S = very abundant in most cells, globular molecules arranged in double helix, usually in high concentration @ cell periphery
- F = cell motility e.g. for phagocytosis
31
Q
describe myosin abundance
A
- low abundance in most cells therefore cannot be seen by microscopy, high abundance in muscle cells (can be seen)
32
Q
microfilament structure and functions
A
- S = actin and myosin filaments (mostly actin in non-muscle) mostly found @ periphery
- F = help give cells shape, skeletal muscle contractions (in sarcomere), movement of cell and plasma membrane (e.g. exo/endocytosis), movement of organelles and vesicles, cleavage of mitotic cells (cytokinesis), reabsorption e.g. microvilli and PCT
33
Q
intermediate filaments
A
- found in epithelium (e.g. skin) as well as other places
- structural support to help keep cells together
- when keratinocytes die, intermediate filaments sit on top of skin as keratin
34
Q
function of peroxisomes
A
- oxidation of fatty acids using generated H2O2
