IMMS: Week 2 Flashcards
What are vesicles
Small, spherical membrane-bound organelles that transport and store material + exchange cell membrane between compartments
Name some examples of vesicles
Pinocytic Phagocytic ER Lysosomes Peroxisomes
What are lysosomes
Site of breakdown for most molecule
Where are lysosomes derived from
Golgi apparatus
What feature of lysosomes allow them to function
Presence of H+ - ATPase which create low pH of 5 to allow acid hydrolyses to function
What are peroxisomes
Small, membrane bound organelles containing enzymes that oxidise long-chained fatty acids
What process are peroxisomes involved with
Beta Oxidation
Define beta oxidation
Breaking down fatty acids into two carbon fragments to generate ATP
What compound is produced by peroxisomes after beta oxidation
Hydrogen peroxide
What is hydrogen peroxide used for
Destroying pathogens
Why is hydrogen peroxide broken down
Can be toxic to cells
What organelle breaks hydrogen peroxide down
Peroxisomes
What is the cytoskeleton
Filamentous proteins which brace the internal structure of the cell - helps maintain shape and internal organisation of cells
Can cytoskeleton be seen under light microscopy
No
What are microfilaments
Actin filaments that form a bracing mesh on the inner surface of the cell membrane
What are intermediate filaments
Anchored transmembrane proteins which can spread tensile force through the tissues
Name 6 types of intermediate filaments
- Cytokeratins
- Desmins
- Glial fibrillary acidic proteins
- Neurofilament proteins
- Nuclear laminin
- Vimentin
Where are cytokeratins found
Epithelial cells
Where are desmins found
Myocytes
Where are glial fibrillary acidic proteins found
Astrocytes
Where are nuclear laminin found
Nuclei of ALL cells
Where are vimentin found
Mesodermal cells
Give an example of a microtubule
Tubulin
Describe the structure of tubulin
Contains alpha and beta chains arranged in groups of 13 to form hollow tubes
What structure do microtubules derive from
Centrosome (2 centrioles)
What cells are tubular found in
All except erythrocytes (no nuclei in erythrocytes)
What is lipofuscin
Membrane-bound orange-brown pigment that causes peroxidations of lipids (degradation) in older cells
Where is lipofuscin found
Heart and liver (old people)
Where are lipids stored
Adipocytes and liver
Where are glycogens stored
Cytoplasm of the liver
What are the basic elements that form molecular building blocks in the body
Carbon Hydrogen Oxygen Nitrogen Sulfur Phosphate
Define the term ‘macromolecules’
Simple molecules such as sugars, lipids and amino acids joining together to form large complex molecules
Give two examples of macromolecules
Haemoglobin, DNA and collagen
What monosaccharides join together to form lactose
Glucose + galactose
What monosaccharides join together to form sucrose
Glucose + Fructose
What monosaccharides join together to form maltose
Glucose + Glucose
What is an aldose monosaccharide
A monosaccharide containing an aldehyde group on C1
What is a ketone monosaccharide
One containing a ketone on C2
What does a typical monosaccharide consist of chemically
A C=O bond, hydroxyl groups and a carbon chain
What does it mean to have a chiral centre
a carbon atom with four different chemical groups attached to it
What are D & L monosaccharides
Optical isomers (same chemical structure but a different 3d arrangement in space)
What are most normal sugars (optical isomer wise)
D
How do cycled ring structures form
Reaction of an aldehyde or ketone with an -OH group of the same molecule
What type of compound is usually seen with a cycle structure
monosaccharides
What is a glycosidic bond
Forms between two monosaccharides (reaction with -OH to another -OH or -NH group)
What are O-glycosidic bonds
These form disaccharides, oligosaccharides and polysaccharides
What are N-glycosidic bonds
found in nucleotides and DNA
What are oligosaccharides
Contain 2 monosaccharides joined by an O-glycosidic bond
How many monosaccharides does a typical oligosaccharide have
3-12
Where can oligosaccharides be found
Product of polysaccharide digestion or part of protein complex
What are polysaccharides -1
Formed by THOUSANDS of monosaccharides joined together by glycosidic bonds
What glycosidic bonds can be found in starch
1,4 alpha glycosidic bonds
What glycosidic bonds can be found in amylopectin
Alpha 1,4 and alpha 1,6 glycosidic bonds
What are proteoglycans
Long-unbranched polysaccharides radiating from a core protein
What are polysaccharides -2
Branched polysaccharide formed from glucose residues.
What linkages can we see in polysaccharides-2
alpha 1,4 (between carbons)and alpha 1,6 (between side and main chain)
Name an example of a polysaccharide-2
Glycogen
Describe the chemical structure of a triglyceride
3 fatty acids bound to a glycerol molecule
Describe the structure of a triglyceride
Contains ester bonds
16-20 carbon atoms in each chain with a methyl group and carboxyl group at the ends
How does the degree of saturation affect a triglycerides melting point
Decreases as the degree of saturation increases
How far apart are double bonds in an unsaturated triglyceride
every 3c intervals
What are nucleotides
Building blocks of DNA
What are purine examples
Adenine and Guanine
What are pyrimidine examples
Thymine
Cytosine
Purine vs pyrimidine
Purine - Two carbon nitrogen rings
Pyrimidine - One carbon nitrogen ring
What are the bonds that exist between bases
Hydrogen bonds
What are the bonds found between the phosphates and sugars in the sugar-phosphate backbone called
Phosphodiester bonds
Why is the phosphate group in a nucleotide important
Source of energy
How many amino acids are there in total
20
What part of an amino acid determines polarity
Side-chains (if they are hydrophilic or hydrophobic
What is the charge of glutamic acid and why
Negative
Two COO- and one NH3+
What optical isomer is amino acid usually seen in
L form
NOTE: Sugars are in D form
What factor effects the charge of the carboxyl and amino groups
pH
How do peptide bonds form
Condensation reaction between carboxyl and amine group
What determines how proteins are different to each other
Sequence of amino acids in the primary structure
What are 5 properties of peptide bonds
- Very stable
- Cleaved by proteolytic enzymes
- Can have partial double bonds
- Flexibility around C atoms not involved in bonds which allows multiple conformations
- Usually a preferred conformation determined by type of side chains and sequence of amino acids
What is a protein
Functional and synthesised by cells
50+ AA
What is a peptide
Less than 50 AA
What is the primary structure of a protein
Sequence of amino acids in the polypeptide chain
What bonds can be found in the primary structure
Covalent bonds
What is the secondary structure of protein s
Formation of alpha helix or beta pleated sheets as hydrogen bonds form between neighbouring amino acids
How is an alpha helix formed
H-bonds between each carboxyl group and the H attached to the N 4 AA along the chain)
How are beta pleated sheets formed
By H bonds between linear regions of polypeptide chains, either from the same protein or two different proteins
What are super-secondary structures
Combination of secondary structures (combination of alpha and beta sub-units)
What is the tertiary structure of a protein
Overal 3D conformation of a protein
What bonds are found in the tertiary structure
H bonds, covalent and electrostatic
What two factors affect the structure of the tertiary structure
Temperature or pH
What is the quaternary structure
3D structure of a protein consists of MULTIPLE SUBUNITS
What are Van de Waals forces
Weak attractive/repulsive forces between atoms due to fluctuating electrical charge
What are hydrogen bonds
Interaction between polar groups
What are hydrophobic forces
Uncharges and non-polar side chains are repelled by water causing them to tightly pack together (aggregate)
What are ionic bonds
Electrostatic attraction between positive and negatively charged ions
What are disulphide bonds
very strong COVALENT bonds between sulphur atoms
Why do we need enzymes
Provides an alternative pathway for the reaction to occur with a lower activation energy
What are enzymes
Biological catalysts that allow reactions to take place at normal body temperature and conditions
How are enzymes regulated
By altering the conc. of substrates, products and inhibitors or activators
What are isoenzymes
Enzymes that have a different structure and sequence but catalyse the same reaction
How does temperature affect enzymes
They only function within a narrow temperature range.
What are coenzymes
These cannot catalyse reactions but help enzymes to do so. These bind with an enzyme protein molecule to form the active enzyme
What are activation-transfer enzymes
Form a covalent bond and are regenerated at the end of a reaction
What are oxidation-reduction enzymes
Involved with reactions where electrons are transferred from one compound to another (NAD and FAD)
What is myoglobin
Found in muscles and acts as a reserve supply of oxygen
-Facilitates movement of O2 into muscles
What structure is found in the centre of myoglobin and haemoglobin
A porphyrin ring which holds an iron atom
What is the porphyrin ring found in haemoglobin and myoglobin called
Haem
What is sickle cell anaemia
Genetic disorder that is characterised by the formation of hard, sticky, sickle-shaped red blood cells (mutation in haemoglobin )
What is the main function of immunoglobulins
Main function is to bind to antigens
Why do antibodies have to bind to antigen s
To target down cells or pathogens marked for destruction by the lysis or complement system
Discuss the structure of an antibody
Look in book
Prokaryotes vs Eukaryotes
Prokaryotes have NO nuclear membrane, and DNA arranged as a single chromosome
Eukaryotes have their DNA in the nucleus bound to protein - a chromatin complex.
Why do we need DNA
- Acts a template and regulator for transcription and protein synthesis
How does DNA polymerase read the template strands
from 3’ to 5’ which allows DNA to be synthesised on daughter strand from 5’ to 3’
What is the daughter strand synthesised from 5’ to 3’
because the phosphate group on the 5’ carbon atom is used by the enzyme as a source of energy for the reaction to occur - ACTIVATION ENERGY FOR THE ENZYME
What element is found on the 3’ carbon atom of DNA
An unreacted oxygen molecule
Why is DNA replication said to be ‘semi-conservative’
Because each resulting DNA double helix retains one strand of the original DNA.
What is the role of topoisomerase
Unwinds the double helix by relieving the supercoils
What is the role of DNA helicase
Separates the DNA apart by breaking the hydrogen bonds between the bases, exposing the nucleotides
What is the role of DNA Polymerase
Reads 3’ to 5’ and synthesises DNA on daughter strand 5’ to 3’ and starts at a primer
What is a primer
Short strand of DNA that s the start point for DNA synthesis as DNA polymerases can only add nucleotides onto an existing strand of DNA
What is a single strand binding protein
Keeps two strands of DNA apart whilst synthesis of new DNA occurs - prevents annealing to form double stranded DNA
What is the role of primate enzyme
RNA polymerase that synthesises the short RNA primers needed to start the strand replication process
What is the role of RNAse H
Removes the RNA primers that previously began DNA strand synthesis
