Life at the Cellular Level Flashcards
What is a cell?
A cell is the fundamental unit of human life.
Why are cells small?
Increased surface area:volume ratio.
What is the role of the cytoskeleton?
Structural support, shape, and facilitation of movement.
What are the elements of the cytoskeleton?
Microfilaments
Intermediate filaments
Microtubules
What is the difference between prokaryotic cells and eukaryotic cells?
Prokaryotic- no nuclear membrane or membrane-bound structures
Eukaryotic- membrane-bound organelles
What can multipotent cells differentiate into?
Cells within a specific tissue.
What can pluripotent cells differentiate into?
Any type of somatic cell.
What are totipotent cells and where are they found?
Found in early embryo- can differentiate into any type of cell.
Describe cellular differentiation.
Cellular differentiation is the process by which cells divide and express different genes which results in the alteration of structure and subsequent behaviours.
Why are cancer cells different to normal cells?
Uncontrolled cell division- do not respond to growth regulation.
What is apoptosis?
Programmed cell death
What is the cell membrane?
Selective barrier which controls entry/exit of substances.
What does the cell membrane consist of?
Phospholipid bilayer structure- hydrophobic/hydrophilic interactions. Amphipathic.
What can permeate the cell membrane?
Water/lipid-soluble molecules.
What does cell adhesion involve?
Junctions found in the epithelia that can link/form barriers to substances.
What is the function of the mitochondria?
Site of aerobic respiration; produces ATP.
What is the function of the nucleus?
DNA storage.
What is the function of the endoplasmic reticulum?
Has ribosomes attached, involved in protein synthesis.
What is the function of the ribosomes?
Protein synthesis
What is the function of lysosomes?
Contain degradative enzymes in membrane.
What are the 4 routes of cell signalling?
Contact-dependent
Panacrine (non-hormones)
Synaptic
Endocrine (hormones)
What are cell surface projections composed of?
Microtubules
Describe cilia.
Short; may present- move with swift power stroke and
Describe flagella.
Longer- usually 1/2 present- movement is snake-like.
What is the underlying root of functional diversity?
Molecular simplicity.
How many elements are part of the structure of organisms?
10- consumed in diet.
What elements make up 90% of humans?
HONC
Why does carbon form the basis of many biomolecules?
Bonding versatility- can form stable bonds with FON atoms.
What are functional groups?
Groups on molecules that can allow classification and give rise to function.
What is polarity and why is it critical to function?
Polarity is a measure of electronegativity between atoms- it affects function because it alters reactivity.
What is a chiral molecule?
Assymetric centre with different attachments.
What are the 5 fundamental reactions of life?
Redox Formation of carbon bonds Internal rearrangements Group transfers Condensation/hydrolysis
What happens in redox reactions?
OILRIG- Oxidation loses electrons, reduction gains them.
What happens during carbon-bond reactions?
Carbon is formed or broken- seen in the cleavage of glucose during glycolysis.
What happens during internal rearrangement reactions?
Molecules are switched about in a rearranged formation. Seen in glycolysis.
What happens during group transfers?
A group is transferred on to a molecule. Seen actively through phosphorylation.
What happens during condensation/hydrolysis reactions?
Condensation involves a molecule being formed with the additional production of water.
Hydrolysis involves the breaking of a molecule using water.
What are polysaccharides?
Polymers of glucose monomers linked by glycosidic bonds.
What are polypeptides?
Initial sequences of amino acids.
What are proteins?
Polymers of amino acids.
What are nucleic acids and what do they consist of?
Polymers of nucleotides joined by 3’-5’ carbon bonds in the sugar-phosphate backbone.
What do nucleotides consist with
Phosphate group, deoxyribose sugar and nitrogenous base.
What allows the formation of the double helix structure in DNA?
Flat planar structure.
What is Retrovir a nucleotide analogue of?
Thymine
What are lipids?
Fats that usually contain one or more fatty acid.
How are fats and oils separated?
Through saturation- determined by the spatial arrangement of carbon atoms within their structures.
Why do forms of energy all interconnect?
Energy is constantly transferred between them.
What do the Laws of Thermodynamics govern?
Energy changes.
What is the First Law of Thermodynamics?
Energy can be converted from one form to another but the total energy of the system (universe) will remain the same.
What is the Second Law of Thermodynamics?
All energy transformations ultimately lead to increased disorder in the universe.
Why can it be argued that cells defy the Second Law of Thermodynamics?
Because cellular processes involve energy changes yet this leads to less disorder within the cell system.
Why do cells not defy the Second Law of Thermodynamics?
They
Why do cells not defy the Second Law of Thermodynamics?
They live in open systems- not in isolation. The chemical reactions that cells use to maintain order release heat and increase entropy in the extracellular environment.
What is Gibbs free energy?
Useful energy.
When can a reaction be spontaneous in a system?
When a system gives up energy (water runs downhill spontaneously, giving up potential energy as it goes), or when it becomes more random and increases in energy.
How do cells carry out thermodynamically unfeasible reactions?
Reaction coupling.
How do organisms overcome the incompatibility of G=0 with life?
By carrying out reactions on a multistep basis using pathways.
What does using a series of reactions maintain?
A dynamic steady state.
How does free energy work in metabolism?
Free energy flows between anabolic and catabolic processes.
What do metabolic pathways involve?
Enzymes.
How do spontaneous reactions interact with equilibrium?
Spontaneous reactions move towards equilibrium but never reach it.
What are intermediary metabolites?
Metabolites between stages; tend to be present in multiple metabolic pathways.
How can ATP produce free energy?
Conversion through hydrolysis to ADP + inorganic phosphate. Can drive thermodynamically unfavourable reactions.
What are some common biochemical reactions?
PEP > Pyruvate
Phosphoryl transfers
Why is food a huge source of energy?
Hydrogen atoms.
What does water do in the body?
Bathes cells, allows transport of soluble substances, enables movement, participates in reactions and dissipates heat.
What enables water to act as a solvent?
Polarity- the O-H bond creates an electronegative attraction and can lead to the development of hydrogen bonding in solvency.
When is hydrogen bonding strongest?
When atoms lie in a straight line.
Why are O2 and CO2 poor solvents in water?
No polarity.
Are charged molecules soluble?
Yes.
Are uncharged molecules soluble?
No.
What are amphipathic molecules?
Molecules that contain both hydrophobic and hydrophilic parts.
Why is water partially charged?
OH- and H+ ions.
What is Kw?
The ion product of water.
How are strong acids/bases recognised?
They can dissociate fully in water.
How are weak acids/bases recognised?
They only have partial dissociation in water.
Are strong acids or weak acids more important in biological systems?
Weak acids- they have less dissociation which gives rise to more properties.
How is pH maintained?
Buffer systems.
What are buffers?
Buffers are solutions of weak acids that allow substances to remain at the same pH even when small amounts of acid or base are added.
How do buffers work?
Double equilibrium system.
What buffer system is present in cells?
Phosphate buffer system.
What buffer system is present in blood/plasma?
HCO3 bicarbonate buffer system.
