Lecture 1: Cells?

Question 1

Prokaryote cell parts

Answer 1

• cytoplasm
• flagellum
• ribosomes
• nucleoid (DNA)
• plasma membrane
• cell wall
• capsule
• plasmid
• pili

Question 2

Plant cell parts

Answer 2

• Rough ER
• Smooth ER
• Ribosomes
• central vacuole
• Tonoplast
• microfilaments
• Intermediate filaments
• microtubules
• chloroplasts
• plasmodesmata
• cell wall
• plasme membrane
• peroxisome
• mitochondria
• Golgi apparatus
• centrosome
• nucleus .. Chromatin, nucleolus, nuclear envelope

Question 3

Animal cell parts

Answer 3

• Nucleus
• Nuclear envelope
• chromatin
• nucleolus
• glycosomes
• smooth ER
• cytosol
• mitochondrion
• centrioles
• centrosome matrix
• microvilli
• microfilament
• microtubule
• peroxisome
• secretion via exocytosis
• Golgi appaatus
• rough ER
• ribosomes

Question 4

Centriole…

Answer 4

Organise spindle fibres in mitosis

Question 5

Glycosome…

Answer 5

a peroxisome involved in glycogen storage & metabolism

Question 6

Lysosome…

Answer 6

small vacuole

Question 7

Eukaryotic cells are packed full of…

Answer 7

MEMBRANES. in 5ml of hepatocytes (teaspoonful) there are ~ 100m^2 of membranes

Question 8

proteins in cells ____ of the volume of the cytosol

Answer 8

20-30%

Question 9

Cytosol…

Answer 9

Aqueous component of the cytoplasm of the cell. Organelles & particles are suspended here

Question 10

Why are cells so small?

Answer 10

• metabolism needs fuel from outside & produces waste products
  - — exchange limited by surface area to volume ratios
• smaller cells are easier to turn over/ replace

Question 11

graph showing SA:V and side length of cube

Answer 11

shorter the side length of cube the higher the SA:V

Question 12

Even small cells can have problems with SA for transports so…

Answer 12

in cells specialised for transport/exchanging materials, SA is dramatically increased and mitochondria abundant. E.g. microvilli in the intestine to absorb nutrients

Question 13

Cell walls e.g. for root hair cells are…

Answer 13

all wiggly and folded = increased SA

Question 14

a coenocytic structure =

Answer 14

multinucleate cells

Question 15

some large cells do exist they often have…

Answer 15

a coenocytic structure with multiple nuclei and chloroplasts & a large vacuole

Question 16

membranes allow,,,

Answer 16

compartmentation

Question 17

why is compartmentation by membranes good?

Answer 17

• different environments (e.g. pH in vacuoles, mitochondria and cholorplasts)
• assists metabolic regulation by keeping enzymes, substrates and regulators separate
• locally high metabolite concentrations
• sequestration of toxic substances
• turnover of substances and organelles
• cells secrete and internalise large numbers of proteins -ER

Question 18

Internal compartments of chloroplasts and mitochondria have an..

Answer 18

acidic pH to drive ATP synthesis

Question 19

Nucleus contents:

Answer 19

genome, DNA replication, transcription, RNA processing, BUT translation is in the cytoplasm

Question 20

Nucleus regulation:

Answer 20

Compartmenting the genome from the cytoplasm allows regulation of gene expression. (e.g. post-transcriptional processing, such as splicing (alternative)).

Question 21

RNA splicing –>

Answer 21

RNA splicing is the process by which introns, regions of RNA that do not code for protein, are removed from the pre-mRNA and the remaining exons connected to re-form a single continuous molecule.

Question 22

Nucleus Transport:

Answer 22

nuclear pore complexes transport RNA, ribosomes, proteins, carbohydrates, signalling molecules and lipids. Small particles (

Question 23

Cytoskeleton:

Answer 23

• protein filaments and motor proteins
• protein filmanets form a 3D mesh -> rigidity, shape & structure
• movement (trackways)

Question 24

In muscle cells, _____, comprises 10% of total cell protein, even in non muscle cells ___ forms 1-5% of cellular proteins

Answer 24

actin

Question 25

Microtubules…

Answer 25

cylindrical tubes (20-25nm diameter) of tubular. Highly dynamic

Question 26

Microfilaments…(& movements)

Answer 26

actin fibres (3-6nm diameter). Movements: gliding, contraction & cell cleavage. With myosin responsible for muscle contraction.

Question 27

Microtubules…

Answer 27

determine cell shape, provide trackway for movement of cell organelles & vesicles. Spindle fibre sin mitosis inside flagella and cilia

Question 28

Intermediate filaments…

Answer 28

(8-12nm diameter) anchor & position nucleus & give cell flexibility

Question 29

cytoskeleton movers (motor proteins)

Answer 29

• all powered by ATP : Kinesin, dynein, myosin (muscle)

- molecules and cargo-containing vesicles (& organelles) are all moved around the cell by motor proteins

Question 30

Kinesin…

Answer 30

travels towards the ‘plus’ end AWAY from the nucleus

Question 31

Dynein…

Answer 31

travels towards the ‘minus’ and TOWARDS the nucleus

Question 32

Actin filaments form…

Answer 32

trackways

Question 33

E.g. of cytoskeleton movement..

Answer 33

Melanocytes. Melanophores used by fish, amphibians, crustaceans, cephalopods & reptiles to change colour. Motor proteins transport pigments in melanosomes along microtubule/actin tracks

Question 34

Microtubules pattern for plant cell wall synthesis:

Answer 34

• Cortical microtubules form a template for deposition of cellulose in bands.
• Turgor-driven plant growth is constrained along the axis of elongation.
• -^–
• • |–
• • |–

Question 35

prokaryote..

Answer 35

any cellular organism that has no nuclear membrane, no organelles in the cytoplasm except ribosomes, and has its genetic material in the form of single continuous strands forming coils or loops, characteristic of all organisms in the kingdom Monera, as the bacteria and blue-green algae.