Week One Practice

What are the four major biomolecule classes?

Carbohydrates, lipids, proteins and nucleic acids.

What are the main functions of carbohydrates?

Energy production, carbon supply and structural support.

What bonds join glucose in cellulose?

β-1,4 glycosidic bonds.

What is the difference between glycogen and starch?

Glycogen stores glucose in animals and is highly branched; starch stores glucose in plants.

What are the main functions of lipids?

Energy storage, insulation, membrane structure and hormone synthesis.

What is the structure of a triglycerol?

One glycerol attached to three fatty acids.

What is the structure of a phospholipid?

Glycerol, two fatty acid tails and a phosphate-containing head.

What are the two main functions of phospholipids?

Form cell membrane bilayers and help emulsify fats.

What bond joins amino acids?

Peptide bonds.

What are the functions of proteins?

Enzymes, receptors, transport, structure, immunity and cell signalling.

What are the three components of a nucleotide?

Phosphate group, five-carbon sugar and nitrogenous base.

What is the difference between DNA and RNA?

DNA contains deoxyribose and thymine; RNA contains ribose and uracil.

What is the structure of the plasma membrane?

A phospholipid bilayer with embedded proteins, cholesterol and carbohydrates.

How are phospholipids arranged in the membrane?

Hydrophilic heads face outward; hydrophobic tails face inward.

What factors affect membrane fluidity?

Fatty acid chain length, degree of saturation and cholesterol.

How does fatty acid chain length affect fluidity?

Longer chains decrease fluidity; shorter chains increase fluidity.

How does fatty acid saturation affect fluidity?

More unsaturated fatty acids increase fluidity; saturated fatty acids decrease it.

What is the role of cholesterol in membranes?

Regulates membrane fluidity and stability.

What is lateral diffusion?

Phospholipids move sideways within the same membrane layer.

What is endocytosis?

The membrane engulfs substances and brings them into the cell.

What is exocytosis?

Vesicles fuse with the membrane and release substances outside the cell.

What is the function of the nucleus?

Stores DNA; site of DNA replication and transcription.

What is the function of mitochondria?

ATP production through cellular respiration.

What is the function of ribosomes?

Protein synthesis.

What is the function of rough ER?

Protein synthesis and processing.

What is the function of the Golgi apparatus?

Modifies, sorts and packages proteins.

What is the function of lysosomes?

Digest cellular waste and unwanted materials.

What is the function of peroxisomes?

Break down fatty acids and detoxify harmful substances.

What is the neuronal communication pathway?

Receptor → sensory neuron → integrating centre/CNS → motor neuron → effector.

What is the function of a receptor?

Detects a stimulus.

What is the function of a sensory neuron?

Carries information toward the CNS.

What is the function of the integrating centre?

Processes information and coordinates a response.

What is the function of a motor neuron?

Carries instructions from the CNS to an effector.

What is an effector?

A muscle or gland that produces a response.

What is the function of dendrites?

Receive incoming signals.

What is the function of the cell body?

Contains the nucleus and integrates incoming signals.

What is the function of the axon?

Carries electrical impulses away from the cell body.

What is the function of axon terminals?

Release neurotransmitters.

What is a synapse?

The junction where communication occurs between cells.

Why does membrane potential exist?

Unequal ion distribution and selective membrane permeability create an electrical difference across the membrane.

What are the four types of gated ion channels?

Ligand-gated, voltage-gated, mechanically gated and leakage channels.

Why do ions move across cell membranes?

To support nerve communication, muscle contraction, cell signalling and cellular balance.

What is depolarisation?

Na+ enters the cell, making the inside more positive.

What is repolarisation?

K+ leaves the cell, making the inside more negative.

What is hyperpolarisation?

Excess K+ leaves the cell, making the membrane more negative than resting potential.

What is a graded potential?

A local membrane potential change that varies in size with stimulus strength and decreases with distance.

What is an action potential?

An all-or-none electrical signal that travels along an excitable membrane without decreasing in size.

What happens when threshold is reached?

Voltage-gated Na+ channels open and an action potential begins.

What happens during action potential depolarisation?

Voltage-gated Na+ channels open and Na+ enters the cell.

What happens during action potential repolarisation?

Na+ channels inactivate and K+ channels open, allowing K+ to leave.

Why does hyperpolarisation occur?

K+ channels close slowly, allowing continued K+ خروج.

What is the difference between graded and action potentials?

Graded potentials vary in size and decrease with distance; action potentials are all-or-none and do not decrease in size.

How is stimulus intensity represented by graded potentials?

Stronger stimulus produces a larger graded potential.

How is stimulus intensity represented by action potentials?

Stronger stimulus produces a higher action potential frequency.

How is a stimulus converted into electrical activity?

Receptors detect stimuli, alter ion channel activity and produce receptor potentials; reaching threshold generates action potentials.

What are the phases of the cell cycle?

G1, S, G2 and M; cells can also enter G0.

What happens during G1?

Cell growth and preparation for DNA replication.

What happens during S phase?

DNA replication.

What happens during G2?

Cell growth and preparation for mitosis.

What happens during M phase?

Mitosis and cytokinesis produce two daughter cells.

What is G0?

A non-dividing state entered from G1; it can be temporary or permanent.

When are cells responsive to mitogens?

G1 phase.

What are mitogens?

Growth signals that stimulate cells to progress through the cell cycle.

What happens when a growth factor receptor is blocked?

Mitogen signalling is prevented, potentially stopping cell cycle progression.

What is the role of cyclins and CDKs?

They form active complexes that phosphorylate target proteins and control cell cycle progression.

What is the G1 DNA damage checkpoint?

Checks for DNA damage and can stop cell cycle progression to allow repair.

What is the restriction point?

A late G1 checkpoint after which the cell is committed to continuing through the cell cycle.

What is the role of p53?

Tumour suppressor that responds to DNA damage by causing cell cycle arrest, repair or apoptosis.

What is the role of pRb?

Tumour suppressor that regulates progression through G1.

What is apoptosis?

Programmed, regulated cell death.

What are the main stages of apoptosis?

Chromatin condensation and DNA fragmentation → cell shrinkage and blebbing → apoptotic bodies → phosphatidylserine exposure → phagocytosis.

What is the role of phosphatidylserine in apoptosis?

Exposed on the outer membrane to signal phagocytes to engulf the cell.

What is necrosis?

Uncontrolled cell death usually caused by injury.

What is the difference between apoptosis and necrosis?

Apoptosis causes cell shrinkage and apoptotic bodies; necrosis causes swelling, membrane rupture and inflammation.

What is cellular senescence?

Permanent cell cycle arrest while the cell remains metabolically active.

What is the role of telomeres in senescence?

Telomeres shorten with repeated divisions; critically short telomeres can trigger senescence.

Where do action potentials normally begin?

At the axon initial segment near the axon hillock.

How do action potentials travel along an axon?

Local currents depolarise adjacent membrane, regenerating the action potential.

Why do action potentials travel in one direction?

The refractory period prevents the recently activated membrane from immediately firing again.

What is a convergent neuronal system?

Multiple neurons send information to one neuron.

What is a divergent neuronal system?

One neuron sends information to multiple neurons.

How does Botox affect neuronal communication?

Blocks synaptic vesicle fusion and acetylcholine release, preventing normal muscle activation.

What is an EPSP?

An excitatory postsynaptic potential that increases the likelihood of reaching threshold.

What is an IPSP?

An inhibitory postsynaptic potential that decreases the likelihood of reaching threshold.

What is temporal summation?

Repeated signals arriving close together in time are added together.

What is spatial summation?

Signals arriving from multiple synapses are added together.

What happens when EPSPs and IPSPs are integrated?

Their combined effects determine whether the neuron reaches threshold and generates an action potential.

What is sensory transduction?

Conversion of a stimulus into an electrical signal by a sensory receptor.

What types of stimuli can sensory receptors detect?

Touch, pressure, sound, light, pain, temperature and chemicals.

What is a monosynaptic reflex?

A reflex with one synapse directly between sensory and motor neurons.

What is a polysynaptic reflex?

A reflex involving interneurons and at least two synapses.

Why are monosynaptic reflexes faster?

They have fewer synapses and less synaptic delay.

What is sensory adaptation?

A reduction in receptor firing during a continuous stimulus.

What is fast complete adaptation?

Receptor firing quickly decreases to zero.

What is slow complete adaptation?

Receptor firing gradually decreases to zero.

What is fast incomplete adaptation?

Initial burst of firing followed by a rapid decrease to a sustained lower rate.

What is slow incomplete adaptation?

Initial burst followed by a gradual decrease to a sustained lower rate.

What is anatomy?

The study of body structures and how they are arranged.

Why is anatomy important in veterinary medicine?

Essential for surgery, clinical examinations, imaging, injections and diagnosis.

What is gross anatomy?

Study of structures visible without a microscope.