Life at cellular Level 1-4 Flashcards
Why are cells so small?
SA:Volume ratio to allow easy absorption and secretion
Prokaryote
0.1-10 micrometres
Bacteria with no membrane bound structures or nuclear membrane
Eukaryote
10-100 micrometres
Human cells
Pluripotent
Capable of becoming all cell types in the body
Multipotent
Cells that can differentiate into many cell types
Cell differentiation
Cells pass through series of changes during development with changes in gene expression
Cell fusion
Cells in muscle divide as single cells then fuse together to form super cells which is a normal process for some cell types
Teratoma
Tumour with tissue or organ components representing normal derivatives of one or more germ layer eg hair, teeth, bone and is a stem cell derived cancer formation
Cancer cell
Divide without any control and fails to co-ordinate with normal cells or to differentiate
Apoptosis
Programmed cell death
Necrosis
Cell death due to disease
Amphipathic
Hydrophilic head and hydrophobic tail
Transport proteins
passive = concentration gradient and small uncharged molecules pass freely Facilitated = non specific (pore) or non specific (channel) transporter
Endocytosis - 2 parts
Phagocytosis - WBC engulfs and triggers phagosome formation
Pinocytosis - Constant removal of cell membrane by nervous system
Exocytosis
Protein produced by rough ER => Golgi apparatus for post transational modification then bud off in a vesicle eg beta cells produce insulin
Cell adhesion
Proteins allow cells to stick together to form tissue
Occluding/tight junction
Seals gap between epithelial cells and is a physical barrier preventing flow
Responsible for the blood brain barrier
Cell to cell anchoring
Link to cytoskeleton and includes adherens junction and desmosome
Adherens junction
Links actin filaments in 2 different cells
Desmosomes
Link keratin (intermediate) filaments in 2 different cells and keratin is not as ordered
Gap junction
Allows passage of small ions from cell to cell for collective communication
Connexins
6 subunit membrane spanning proteins allowing “1” cytoplasm
Cell matrix anchoring junctions
Stops epithelial cells ripping away and get actin linked cell matrix adhesion and hemidesmosomes
Paracrine
Signals to cells in local area
Endocrine
Signals to cells in multiple tissues and has multiple effects as will travel in the bloodstream
Fast response (proteins)
Proteins altered and changed
Slow response (proteins)
Genes activated on/off and changes the protein synthesis
What protein is found in the outer membrane of the mitochondria?
Porin protein
Nucleus
Contains DNA (including euchromatin which is not as dense and the genes are active and also heterochromatin which is densely wrapped), nucleoprotein which is DNA wrapped around protein and RNA
Nucleoli
Site of rRNA and ribosomal assembly
Smooth ER
Breakdown compounds including drugs and glycogen and synthesises lipids
Lysosomes
Separate enzymes with digestive bacteria in vesicles to protect the rest of the cell and can be used in autophagy (recycle cellular components) or digestion of engulfed particles like bacteria
Cytoskeleton
Supports and maintains the shape of the cell and also anchors and moves organelles
Cytoplasmic screening
Directed flow of cytosol and organelles
Microfilaments
- Actin = dynamic and directionality
- Collagen = subunits of protein added together
Intermediate filaments
Hold pieces of cell in right place
Microtubules
Associated with nucleus for mitosis
What 2 structures are made from microtubules
Cilia ( short and many with a stiff stroke) and also flagella where there are 1 or 2
3 similarities seen at basic level
- elemental level
- molecular level
- Reactions that occur
10 structural elements
C,O,N,H,K,P,Na,S,Cl, Ca
12 trace elements include
Zn, Fe,Mg etc are metal ions that form integral parts of protein structure
Lightest atoms form the ________ bond
Strongest
Configuration
The fixed arrangement of atoms in a molecule eg cis or trans changed only by making or breaking bonds
All proteins are made from L or D amino acids?
L
Chiral centre
Assymetric carbon with 4 different functional groups with the 2 forms laevo or dextro
Conformation
Precise arrangement of atoms in a molecule eg amino acids and bond rotation
5 reactions of life
- Redox
- making and breaking C-C bonds
- internal rearrangements
- Group transfers
- condensation and hydrolysis
Biological redox
2 electrons and 2 protons gained/lost
2 H+ one molecule to another in dehydrogenation reactions eg. recycling of NAD
Making/breaking C-C
cleavage of glucose in glycolysis
Internal arrangements
Trace elements eg Mg needed for glucose =>fructose
Group transfer
High energy phosphate fructose-6-phosphate => fructose-1.6- biphosphate
Condensation and hydrolysis
polysaccharide monomers joined to give sugars by condensation
Bonds used to link one carbohydrate group to another
Glycosidic bonds
Proteosomes
Protein complexes which degrade unneeded or damaged proteins by proteolysis
Nucleic acids
Polymers of nucleotides joined by 3’,5’ - phosphodiester bonds
Pyrimidines
3 H2 bonds, flat, single ring - C U T
Planar
2 H2 bonds, flat, double ring - A G
ZDV/AZT
Similar to thymine nucleotide and prevents integration of HIV
Starch and glycogen are polymers of ___ glucose
D - linear form has aldehyde group which can be oxidised
Is glucose a reducing sugar?
Yes
Cyclic form of glycogen and starch means
Only end monomer remains linear to allow for a reducing end
Energy
Heat, light, mechanical, electrical
Energy change law 1
Energy can be converted from one form to another but the total energy of the universe remains the same
Entropy
Randomness/chaos in a closed system
As useable energy decreases and unusable energy increases entropy increases or decreases?
Increases
Enthalpy
Heat released to surroundings reflecting number/kinds of bonds broken/formed
Spontaneous reaction
Once it starts comes to an end and finishes
Energy coupling
Carry out thermodynamically unfavourable reaction by coupling to a catabolic reaction which will drive the anabolic reaction
Metabolism
Chemical process in a living organism by which food is used for tissue growth or energy production
Exergonic
Catabolism which releases energy delta G is +ve
Endergonic
Anabolism which uses energy delta G is -ve
Electron motive force
Electrons accomplish work as they pass through chemical intermediates and drive a particular protein to spin around
Water main functions
- Bathes our cells
- Dissipates heat
- Dissolves and transports compounds
- Involved in reactions
Molecules that form hydrogen bonds dissolve in water
water-water and solute-solute replaced with energetically favourable water-solute hydrogen bonds
Transport of oxygen
Haemoglobin transports oxygen and protein dissolves in water
Transport of carbon dioxide
Transported as bicarbonate due to polarity
Charged molecules dissolve
Water forms screens around the ion
Ionic product of water
Kw = [H+]{OH-] = 1x10^(-14) moll^(-2)
pH
pH +pOH = 14 and -log[H+]
Buffers
Solution of weak acid ( eg glycine) and salt
An acid is a proton
donor
A base is a proton
Acceptor
Henderson - Hasselbach equation
pH = pKa = log [A-]/[HA]
Phosphate buffer
H2PO4 - <=> H+ + HPO42-
In cells
Bicarbonate buffer
H2CO3 <=> H+ + HCO3-
In blood pH = 7.4
