Life At The Cellular Level - Cells & Molecules Flashcards
What are some similarities and differences between prokaryotic and eukaryotic cells?
Both have cytoplasm, ribosomes and cell membrane.
Prokaryotes (bacteria) don’t have any membrane bound organelles. Don’t have nuclear membrane
Eukaryotes have membrane bound organelles. Nucleus with a membrane
Briefly describe the cell membrane
Plasma membrane is made of a phospholipid bilayer, it is selective and decides what is allowed to enter or exit the cell.
Protein receptors are embedded in it, detect chemical messengers and signals in the extracellular fluid.
What is the sructure and function of the cytoskeleton?
Made of fibres (micro filaments, intermediate filaments and micro tubules). Protein fibres of cytoskeleton connect to protein fibres in the extracellular space to form cells into tissues.
Helps maintain cell shape.
Transports organelles around the cell (intracellular transport)
Allows the whole cell to move.
Holds organelles in place (internal cell order)
What is the nucleus?
Enclosed by nuclear membrane (phospholipid bilayer)
Contains DNA, is the brain of the cell.
What is the endoplasmic reticulum and Golgi apparatus?
Endoplasmic reticulum can be smooth or rough.
RER contains ribosomes (site of protein synthesis), it modifies proteins.
SER has no ribosomes, produces lipids, steroid hormone and metabolises toxins.
Golgi apparatus packages proteins for transport out of the cell.
Briefly describe the mitochondria
Produces energy in the form of ATP
Outer membrane has pores
Has cristae (inner membrane folds) to increase surface area and energy production.
Matrix contains most of the enzymes required to metabolise food.
What are lysosomes and peroxisomes?
Both are membrane bound vesicles containing enzymes. The enzymes catalyse reactions and so must be stored away until needed.
Lysosomal enzymes are degradative, they digest biological materials or engulfed particles (e.g bacteria).
Peroxisomal enzymes degrade long fatty acid chains and other foreign toxic molecules. These reactions are produce hydrogen peroxide which is toxic so the peroxisome breaks it, protecting the cell.
What are 2 types of stem cells?
Multipotent - can differentiate into many cell types
Pluripotent - can differentiate into any cell type.
What are the 2 processes of cell death?
Apoptosis - programmed cell death, a normal process
Necrosis - untimely death of cells usually caused by illness or injury. Not a normal process and can lead to cancer.
When cells don’t die the way they should, uncontrolled cell division may take place, cells may fail to differentiate, normal/healthy cells may be replaced by damaged cells
What are the major elements of human biomolecules?
Hydrogen
oxygen
nitrogen
carbon - most versatile, can for single bond with H, single or double with O and single double or triple with N
Configuration vs Conformation
Configuration is the fixed arrangement of atoms in a molecule. The double bond between carbon and carbon is rigid, therefore can only have 2 configurations (cis and trans).
Cis- both groups on same side
Trans- groups on opposite sides
Conformation - the spatial arrangement of groups that can have different positions in space due the freedom of a single bond to rotate.
What are the 5 reactions that can take place in living organisms?
Give examples
- Redox reactions
NADH is an reducing agent, itself is oxidised
NAD+ is an oxidising agent, itself is reduced - Making and breaking of carbon to carbon bonds
Making - glyconeogenesis
Breaking - glycolysis - Internal rearrangements
Glycolysis - Group transfers
Glycolysis
Phosphoryl group is transferred from ATP to fructose 1,6-biphosphate. - Condensation and hydrolysis
Condensation is when two smaller molecules are combined into one larger molecule, releasing water
Hydrolysis is when a larger molecule is broken down into smaller molecules, using water.
The subunits of polysaccharides, proteins and nucleic acids are all joined by condensation reactions and broken by hydrolysis reactions.
What are 3 types of carbohydrates?
Monosaccharides (glucose)
Disaccharides (sucrose)
Polysaccharides (glycogen)
Glucose polymers start by condensation reactions between 2 glucose molecules.
What at proteins?
(Brief)
Long chains of amino acids.
Amino acids are joined by condensation reactions - the amino group of one amino acid reacts with the carboxyl group of another and a molecule of water is released. A peptide bond forms between the amino acids
What are purines and pyrimidines?
Purines= guanine and adenine
Pyrimidines= thymine, cytosine and uracil
