Basic Biology Flashcards
Enzymology, Cell Organelles, Membrane Structures and Components, Biomolecules, Nutrients and Vitamins, Meiosis, Cell Proliferation and Mitosis, Cell Specification.
What is metabolism and what is the purpose of it?
Chemical reactions that occur in a living organism. The purpose is to produce energy, biosynthesis and excretion.
Define anabolism.
Synthesis of larger molecules from smaller ones (requires energy).
Define catabolism.
Synthesis of smaller molecules from larger ones (releases energy).
What are the 5 types of electron carriers?
Flavoproteins (NADH/NAD+) Cytochromes (haeme in haemoglobin) Copper atoms in mitochondrial membrane Uniquinane/Co-enzyme Q Iron-sulfur proteins (Fe3+/Fe2+)
Purpose of ATP.
Used as an energy intermediate. Produces 7.3kJ of free energy when hydrolysed.
Purpose of Enzymes.
Biological catalysts.
6 Types of Enzymes.
Transferase Ligase Oxidoreductase Isomerase Hydrolase Lysases
Characteristics of Enzymes.
- Globular Proteins
- Control metabolic reactions rate
- Lower activation energy
- Not consumed (re-usable)
- Substrate specific
- Shape of active site determines substrate
Define substrate.
The reactant.
Define active site
Region where substrate binds + undergoes chemical reactions.
Define co-factor.
Inorganic ions (Ca2+) which may be charged during the reaction.
Define co-enzyme.
Organic non-protein molecule (NAD+) that are a subset of co-factors.
Define prosthetic group.
A co-factor permanently attached to an enzyme.
Define apoenzyme.
Enzyme with a co-factor removed (inactive catalytically).
Define haloenzyme.
Enzyme with co-factor attached.
Describe the Lock-and-Key model.
- Active site is rigid shape
- Substrate needs to be matching shape
- No change in the active site shape
Describe the Induced fit model.
- Active site is flexible
- Shape of enzyme, active site + substrate adjust (improves catalytically)
- Greater range of substrate specificity
How does temperature effect enzyme activity.
Increases until reach optimum temperature where the enzyme begins to denature causing a decrease in activity.
How does pH effect enzyme activity.
Enzymes need to be around optimum pH decreases otherwise -> Specific to each enzyme.
How does substrate concentration impact enzyme activity.
Maximum activity occurs when all enzymes are saturated so it will reach maximum reaction velocity.
How do competitive inhibitors effect enzyme activity.
They are a similar shape to substrate so they bind to the active site meaning substrate can no longer bind.
How do non-competitive inhibitors effect enzyme activity.
Different shape to substrate but bind to enzyme in a allosteric place which alters shape of the active site meaning substrate no longer complimentary.
Describe allosteric modulators.
Can be inhibitors or activators but are different shaped to the substrate and are involved in feedback inhibition (switches process off when not needed).
Importance of enzymes.
Can be:
- Diagnostic markers of diseases
- Biochemical estimations + detections
Characteristics of Prokaryotic Cells.
-> Bacteria and Archaea
- Single-celled with DNA being circular
- Lack organelles
- DNA in nucleiod, no separation
- Rigid cell walls
- Functional structures in cytoplasm
Have Pili or Fimbriae and some have flagella
Characteristics of Eukaryotic Cells.
- > Animals and Plants
- Single of multicellular
- Contain organelles - which are specialised for their function
- DNA organised into chromosomes in the nucleus
- Nucleus surrounded by cytoplasm
Types of Cytosol organelles.
Mitochondria, Endoplasmic Reticulum (ER), Golgi apparatus, Lysosomes, Peroxisomes
Types of Inclusions.
Lipid droplets, Glycogen granules, Ribosomes
Types of Protein Fibres.
Cytoskeleton, Centrioles, Cilia, Flagella
Describe Sub-Cellular Fractionation.
- Disruption of plasma membrane
- Ultracentrifugation
- Cell compartments separate based on size and density
- Further density-gradient centrifugation can separate individual components from each fraction.
Describe Cell Membrane.
Phospholipid bilayer Physical isolation Regulation of exchange Communication Structural support
Describe Cytoplasm.
Semi-fluid material surrounding organelles
Site of many cellular activities
Offers cell support
Medium for internal cellular transport
Describe Nucleus.
Cells control centre
Regulates all cellular activity
Contains DNA (hereditary information)
Consists of nucleoplasm bounded by nuclear envelope (Two membranes - Inner/Outer/Pores)
Nucleolus - Transcribes and assembles rRNA
Chromatin - DNA looped around histone proteins
Nuclear pores - Allows communication between nucleus and cytosol, Ions + small molecules pass freely, Allows cell to restrict DNA to nucles
Describe Endoplasmic Reticulum (ER).
A system of folded, interconnected membrane vesicles.
- Large flattened sac-like structures (cisternae)
- Internal space = Lumen
Describe Smooth ER.
No ribosomes
Biosynthetic + Biotransformational activities (Lipids/Steroids/Steroidal hormones) - in liver/kidney
Describe Rough ER.
Ribosomes on cytosolic side
Site of protein synthesis -> Protein transported to lumen for modification
Describe Golgi Apparatus.
Large sac-like membrane vesicles, associated vesicles + tubules
Processing station
- Package + distribute cell products (for internal/external use)
- Vesicles budding off ER travel and are accepted by Golgi
- Vesicles budding off Golgi travel to other organelles/cell surface
Describe Vesicles.
Similar membrane to plasma membrane
Internal conditions different to cytosolic environment
Describe Vacuoles.
Component for storage + transport (often temporarily)
Largest in plants
Describe Lysosomes.
Membrane bound vesicles used in intra/extracellular digestion of biomolecules + old cells.
Characteristics: 0.5-1um, Contain lysozymes, Lumen has low pH, Acid hydrolases (active at low pHs).
Special carbohydrate to prevent self-destruction
Larger amount in white blood cells
Describe Peroxisomes.
Membrane bound from ER
Characteristics: 0.1-1um, Contain oxidase + catalase, Detoxify + decompose harmful substances
Lots in the liver
Describe Vesicles Transport.
Move molecules in a cell
Recognise + fuse with target membranes
Describe Secretary Vesicles.
Contains materials to be excreted from the cell
- Removal of waste
- Release chemical signs (hormones)
Vesicle fusion (Full/Kiss-and-run - reusable)
Describe Mitochondria.
Site of aerobic respiration + energy production
Double membrane:
- Inner = Folded forming cristae
- Area within cristae = matrix
- Gap = Inter-membrane space
Membrane in inter-membrane space allow for cell death (apoptosis)
Distribution in cells + tissue depend on function (muscles = high)
Matrix - Contains enzymes, ribosomes, granules, DNA, machinery to form ATP
Describe Cytoskeleton.
3D structure that fills the cytoplasm Roles: - Cell Movement - Cytokinesis (cell division) - Organisation of organelles
Composed of:
- Microfilaments = 3-6nm, threadlike, mainly actin, carry out movement
- Microtubules = 20-25nm, cylindrical tubes, a + B tublin subunits, determine cell shape, used for flagella + cilia movement
- Intermediate filaments = 10nm, overlapping + twisted conformation, provide tensile strength, anchor organelle + nucleus, form junctions between cells + matrix
Describe the Structure of the Cell Membrane Lipids.
Most membrane lipids are amphipathic
Many are phospholipids (glycerophospholipids/sphingolipids)
Sterols have stabilising roles
Proteins are associated to surface/span membrane
Describe Glycerophospholipids.
Glycerol as polar head
Attached to a phosphate ion and an R-group
Helps to fine tune membrane properties
Describe the two types of Sphingolipids.
Sphingomyelin = Phosphocoline head group Glycosphingolipids = Mono/oligo-saccharide head group
Explain the Main Constituents of a Cell Membrane.
Phospholipids = Membrane formation Glycolipids = Antigen recognition Sterols = Membrane fluidity Proteins = Signalling
State the 7 types of Amphipathic Phospholipids.
Phosphatidylcholine (PC) Phosphatidylethanolamine (PE) Phosphatidylglycerol (PG) Phosphatidylinositol (PI) Phosphatidylserine (PS) Diphosphatidylglycerol (DPG) Sphingomyelin (SP) - Animals
State the 2 types of Gylcolipids.
Cerebrosides (mono)
Gangliosides (oligo - inc sialic acid -ve charged)