TBBOL- Week 9

Are prokaryotes or eukaryotes typically smaller?

Prokaryotes.

What encloses both prokaryotes and eukaryotes?

The plasma membrane.

How are bacteria divided?

By binary fission.

How are eukaryotes divided?

Mitosis and meiosis.

What type of ribosomes are in prokaryotes and eukaryotes respectively?

70s and 80s.

What does the extracellular matrix consist of?

Collagen fibres, laminins and proteoglycyns.

What does the plasma membrane consist of?

Phospholipids, glycoproteins, integral proteins, protein channels and peripheral proteins.

How are substances able to get into the cell?

Diffusion, permeation, facilitated transport, active transport and through vesicles.

How do large things get into the cell?

Through phagocytosis, pinocytosis and receptor-meditated endocytosis.

What are the stages of the cellular digestion system?

They acidify and fuse with lysosomes, maturation, sorting and neutralisation occurs and finally exocytosis.

What are some of the unique components of mitochondria?

It is a double membrane-bound organelle and it has its own replicating circular DNA and own ribosomes.

What is the internal membrane of mitochondria folded into?

Cristae.

What is the mitochondria responsible for?

Fission and aerobic respiration.

What is the internal membrane of the chloroplast folded into?

Thylakoids.

What does gene transcription into mRNA in the nucleus create?

An “order” message.

What controls gene regulation?

Transcription factors.

What is the defining characteristic of a eukaryotic cell?

The nucleus.

What separates transcription and translation?

A double membrane.

What do DNA and histones form?

Chromatin.

How do macromolecules enter or exit the nucleus?

Via nuclear poles.

Where can proteins be released into?

The cytoplasm or directly into the lumen of the RER.

What are polysomes?

Large amounts of the same protein which are needed for translation.

What are some of the modifications that can occur within the RER lumen?

Protein folding, assembling into multimeric complexes, glycosylation, formation of disulphide bridges, protelytic cleavage and prenylation.

Where are modified proteins translated to?

The Golgi apparatus.

What are the three sections of the Golgi apparatus?

Cis, medial and trans.

What do vesicles from the ER fuse with?

The Golgi apparatus.

Where are proteins directed to after going through the Golgi apparatus?

The plasma membrane or lysosome.

What is clathrin?

A scaffolding network that cages the vesicle.

What does the cytoskeleton consist of?

Microtubules, microfilaments and intermediate filaments.

What are vesicles transported through the cytoskeleton by?

Microtubules.

What is the name of the process where vesicles fuse with the plasma membrane and release their contents to the extracellular environment?

Exocytosis.

What do most eukaryotic cells have which protrudes from the cell surface?

Flagellum.

What is flagellum anchored by?

Basal bodies in the cytoplasm.

What are the main components of flagellum?

Microtubules, dynein and nexin.

What organises microtubules and the mitotic spindle?

Centrioles (MTOC).

What is the differences in plant and animal cells?

Plant cells have no centrosomes whereas animal cells have no chloroplasts, cell wall or vacuole.

What can soap molecules do?

Detach, seal, turn spherical, fragment or can fuse.

What causes asymmetry in the lipid bilayer?

The lack of “flip-flopping”.

What determines membrane fluidity?

Lipid composition, temperature and cholesterol content.

What does asymmetry in the lipid bilayer cause?

For a difference in the intracellular and extracellular environments.

What are the two properties that influence whether a particle can permeate the plasma membrane without assistance?

Solubility of the particle in lipid and the size of the particle.

What are some of the things required for transport over the plasma membrane?

A pathway and a driving force (passive or active).

What is membrane permeability determined by?

Hydrophobicity, size and charge.

What is diffusion?

Unassisted membrane transport.

What does net diffusion lead to?

An unequal distribution of molecules.

What are some of the factors which can affect the rate of diffusion?

The magnitude of the concentration gradient, the surface area of the membrane, the lipid solubility, the molecular weight of the substance and the distance through which diffusion occurs.

What two things can act on an ion at the same time?

An electrical and concentration gradient.

What is the name for the net effect of a simultaneous electrical and concentration gradient on an ion called?

The electrochemical gradient.

What is osmosis?

The net diffusion of water down its own concentration gradient through a selectively permeable membrane.

What is osmolarity?

The concentration of osmotically active particles present in a solution.

What is tonicity?

The effect a solution has on cell volume.

What effect does isotonicity have on cell volume?

No effect.

What effect does hypotonicity have on cell volume?

The cell will swell.

What effect does hypertonicity have on cell volume?

The cell will shrink.

What are the two mechanisms for selective transport?

Carrier-meditated transport and vesicular transport.

What are some examples of carrier-meditated transport?

Facilitated diffusion and active transport.

What are some examples of facilitated diffusion?

Transporter and channel proteins.

What occurs in carrier-meditated transport?

Molecules bind onto a specific carrier which undergoes a conformational change.

What are the three important characteristics that determine the kind and amount of material transferred across the membrane?

Specificity, saturation and competition.

What are three classifications of transport?

Antiport, uniport and symport.

What are the directions of uniport, symport and antiport respectively?

Uniport is the same direction, symport is also the same but with two differing binding sites and antiport is transported in opposite directions.

What are the transports in active transport meditated to?

An energy source.

What are some of the differences between primary and secondary active transport?

Primary active transport directly uses energy to move a substance whereas secondary active transport does not.

What are the three roles of the sodium-potassium pump?

It establishes sodium and ion gradients across a plasma membrane, it regulates cell volume by controlling concentration of solutes inside a cell and the energy used to drive to pump also acts as the energy source for secondary transport.

What is endocytosis?

The pinching off of membrane to engulf a substance.

What is exocytosis?

A vesicle fuses with the plasma membrane to release its content to the ECF

What are the four steps to vesicle fusion?

Tethering, docking, priming and fusion.

What do Rab proteins do?

They guide and transport vesicles to the target membrane.

What are the three origins of life?

Bacteria, archea and eukarya.

What is taxonomy?

The practice and science of categorisation and classification of organisms.

What are branch lengths proportional to in a phylogenetic tree?

The evolutionary time between related organisms.

What organism has the highest genetic diversity?

Bacteria.

What are some of the specialised functions of capsules and S-layers?

Protection, attachment and motility.

What type of molecules commonly have capsule and slime layers?

Polysaccharides.

What is the slime layer?

A regularly structured protective layer composed of glycoproteins.

Where are slime layers found?

Bacteria and archaea.

What are some of the characteristics of the cell wall?

It is rigid and protects the cell from osmotic pressure and pathogenicity.

What are sex pili?

Hollow tubes which can be coded as sex factors/

What are fimbrias?

Shorter tubes that are important in surface attachment.

What are the four types of flagellum?

Monotrichous, amphitrichous, lophotruchous and peritrichous.

What is actin responsible for?

Cell growth and shape.

What do intermediate filaments control?

Curved shapes.

What are inclusion bodies responsible for?

Storage (glycogen), floating (gas vacuoles), photosynthesis (cyanobacteria) and magnetic navigation (magnetosomes).

What are endoscopes used for?

The survival of harsh conditions.

What do bacterium have instead of a nucleus?

Nucleoids, DNA-scaffolding proteins and plasmids.

What do archaea utilise?

Various energy sources such as light, metal ions and hydrogen.

What do archaea use in their cell wall?

Pseudopeptidoglycan.

How are side chains linked in an archaea’s cell membrane?

Ether-linked.

What is DNA sequencing?

The determination of nucleotide sequences of DNA.

What is metagenomics?

The sequencing of DNA fragments from environmental samples.

What are Asgard archaea?

Newly-sequenced meta-genomes of archaea from deep sea sediments and hot springs.

Where do eukaryotes perform in the nitrogen cycle?

Ammonification.