Life at the Cellular Level 1-3 Flashcards
Describe the structures present in all cell types.
Cytoplasm - site of chemical reactions.
Ribosome - produce proteins from amino acids
Cell (plasma) membrane - Regulates the transport of materials entering and exiting the cell.
Define the roles of eukaryotic animal cell organelles: nucleus, endoplasmic reticulum,
ribosome, Golgi apparatus, lysosome, peroxisome, mitochondrion, flagellum, cilium.
Nucleus - Contains DNA
Endoplasmic reticulum - Smooth, is associated with lipid and steroid hormone production and metabolism of toxins
Rough - (has ribosomes attached) and modifies proteins
Ribosome - synthesises proteins
Golgi appartus - packages up protein in preparation for transport out of the cell.
Lysosome - Lysosomal enzymes are degradative and they are responsible for the digestion of biological materials (cells own materials; autophagy) or digestion of engulfed particles (e.g. bacteria).
Peroxisome - Peroxisomal enzymes degrade long-chain fatty acids and other foreign toxic molecules. These reactions generate hydrogen
peroxide, which is toxic. Peroxisomes break the hydrogen peroxide (catalase enzyme) protecting the cell.
Mitochondrion - Matrix contains most of the enzymes required for metabolising food molecules (e.g. Krebs cycle) and provides the cell with energy
Flagellum - surface projections supported by the cytoskeleton. longer, usually one or two present, movement is snakelike (or like a wave)
Cilium - surface projections supported by the cytoskeleton.
Cilia: short, usually many present,
move with stiff power stroke and
flexible recovery stroke.
Correlate organelle structure with function. (RER, Golgi apparatus, lysosmes, mitochondria
RER -
Describe the structure and function of the eukaryotic plasma membrane.
Comprises a double layer of lipid with attached phosphate groups = phospholipid bilayer. Forms a selective barrier, being choosy about what it allows to cross in or out of the cell. Embedded in the membrane are proteins which act as receptors to detect chemical messengers and signalling molecules in the fluid surrounding cells (extracellular fluid).
Define the role of the cytoskeleton.
- Supports and maintains cell shape.
- Holds organelles in position – internal cell order.
- Helps move organelles around the cell – intracellular transport.
- Drives and guides cellular migration – movement.
5.Protein fibres of the cytoskeleton connect with protein fibres in the extracellular space – Assembly
of cells into tissues.
Define stem cells and describe cell differentiation.
Undifferentiated stem cells divide and give rise to daughter cells, which are genetically identical. Differences in gene expression and the local cellular environmental cause the daughter cells to develop into different cell types.
Outline the difference between apoptosis and necrosis.
- Apoptosis is controlled, programmed cell death. It is a normal process and essential for normal function.
- Necrosis on the other hand describes the untimely death of cells in response to injury or infection. It is not a normal process.
Define the major elements used to construct human biomolecules.
- Four organic basic elements (basic
components of macromolecules):
H, C, N, O. It is believed the bonding versatility of C explains why it forms the basis of almost all
biomolecules.
State the importance of chemical functional groups and molecular configuration and conformation in determining biomolecular function.
Each one confers different specific chemical properties and so has different functions based on the group. Configuration – the fixed arrangement of atoms in a molecule. Many biomolecules contain a double bond between carbon atoms (C=C) which is rigid (no freedom of rotation). They can therefore only interconvert
between the two by breaking and
re-forming bonds (energetically expensive!) Can therefore only have two distinct configurations: cis/trans.
List and give examples of the five kinds of chemical reaction occurring in living organisms.
+ Redox - OILRIG, Conversion of NAD+ (oxidising agent) into NADH (reducing agent)
+ Making and breaking c-c bonds - Breaking = glycolysis, Making = gluconeogenesis
+ Internal rearrangements - Glycolysis
+ Group transfers - Glycolysis
+ Condensation (Combining to form a larger molecule) and hydrolysis reactions (Breaking down a larger molecule into subunits using water) - Glucose joining together to make maltose
Describe the general structures of proteins, nucleic acids, polysaccharides and lipids.
Proteins, nucleic acids, polysaccharides and lipids are polymers formed by amino
acids, nucleotides, monosaccharides and fatty acids, respectively, joined together. Nucleic acids are polymers of nucleotide monomers linked by 3’,5’ phosphodiester bonds.
Define the term ‘hydrogen bond’.
Forms when 2 polarized molecules
form a non-covalent bond known
as a hydrogen bond. Electrons are shared unequally between molecules.
Describe the interactions between water molecules and solutes that determine solubility.
Note; Lipids are hydrophobic
- Hydrophobic: Doesn’t dissolve in water, they arrange themselves to minimise contact with surrounding water molecules.
- Hydrophillic: Easily dissolves in water as water forms a screen around charged particles. e.g. Alcohols
- Amphipathic - Has different sections of molecule some of which is hydrophobic and some is hydrophillic. Many proteins are amphipathic.
Define the term ‘pH’ and explain the importance of the Henderson-Hasselbalch equation.
pH is the way of designating the concentration of H+ in any aqueous solution. The Henderson-Hasselbalch equation can be used to calculate how the pH of a physiological solution will respond to changes in either the conjugate acid or base.
Describe the difference between a micelle, a liposome and chylomicron
Lisposomes and micelles are used as drug-delivery systems. Liposomes have a double membrane with a hollow center specific to that suspension. Micelles have a single membrane for hydrophobic drugs. Chylomicron ike a liposome with protein
embedded in the shell, and lipid stored in the core.The phospholipid heads and outer edges of the
proteins form a hydrophilic outer shell.The hydrophilic shell is essential to allow the chylomicron to be transported in the aqueous plasma of the blood.
