CELL BIOLOGY

Question 1

Basic way cells are formed

Answer 1

from direct assembly of macromolecular components

Question 2

what is the lower limit of cell size

Answer 2

must be large enough to contain components
required to program and maintain metabolism

Therefore Mainly the logistics of metabolism set cell size limits

Question 3

what is the upper limit of cell size

Answer 3

small enough for high SA:Vol to satisfy diffusive entry of needed molecules.

Therefore Mainly the logistics of metabolism set cell size limits

Question 4

why do small cells have a larger SA:VOL ratio

Answer 4

SA increases by a power of 2 whereas volume increases by a power of 3, therefore smaller cells have a larger SA relative to vol.

Question 5

what are the different classifications of prokaryotes

Answer 5

mycoplasms: parasitic, small bacerium organisms

bacteria eubacteria: free living, parasitic, in soil or water

bacteria archaebacteria: in bogs, ocean depths and hot springs

Question 6

Most prokaryotes are single cells with:

Answer 6

cellwall
plasma membrane
cytoplasm
internal involutions (foldings provide high sa)
Dna in circular strand

Question 7

what are the basic functional requirements of cells

Answer 7

• protective coat (cell wall, cytoskeleton)
• enclosing semi permeable membrane
• biochemical components
• allow molecules to enter exit cell
• genetic material for replication
• specialised regions for specific functions

Question 8

Outline the steps of cell evolution

Answer 8

1. Abiotic synthesis of organic molecules from inorganic matter and electric charge
2. Polymerisation of organic molecules (self arrangement)
3. Aggregation of polymers and molecules into separate areas of environment
4. Capacity of hereditary/self-replication (RNA?)

Question 9

What is a protobiont

Answer 9

protobionts cause basic metabolism as they are protein-like compounds.

Question 10

describe gene evolution

Answer 10

lottery for monomers to abiotically form

Question 11

describe the first basic ribosome

Answer 11

random polypeptide catalyst + rna

Question 12

prok and euk differences

Answer 12

prok

• circular DNA localised in nucleoid
• no membrane bond organelles

euk

• linear DNA molecules
• complex endomembrane system
• range of organelles with specific feautres
• cytoskeleton and cellular motion

Question 13

how to develop a eukaryotic cell

Answer 13

1. membrane in-foldings to form endomembrane system

2. serial endosymbiotic events including aerobic prokaryote (mitochondria) photosyntheic prokaryote (chloroplasts)

Question 14

what is the endomembrane system

Answer 14

a system of internal, membrane-bound compartments with physical links to exchange components.

Question 15

outline the nucleus

Answer 15

• contains DNA for genes, proteins, replication
• nucleolus inside produces RNA and assesmbles ribosomal sub-units
• nuclear enevelope encloses nucleus with an inner and outer membrane supported by cytoskeleton
• continous with E.R
• nuclear pore complexes cotnrol entry/exit
• intermediate filaments hold nucleus in place

Question 16

outline ribosomes

Answer 16

• consist of rRNA and proteins
• carry out protein synthesis (translation)
• free or bound to ER.

Question 17

outline Endoplasmic Reticulum

Answer 17

smooth

• metabolises carbs
• makes lipids
• detoxification
• stores calcium

rough

• proteins passed to lumen
• can produce glycoproteins
• makes phospholipids and proteins to assemble membrane

Question 18

outline golgi apparatus

Answer 18

• receives, sorts and ships around the cell

- vesicles fuse at cis-golgi (facing nucleus) to form new cristae (long things). new vesicles bud off trans-golgi

Question 19

outline lysosomes

Answer 19

• vesicles full of hydrolytic (digestive) enzymes
• autophagy (breaking down) occurs in highly acidic environment
• protease sucks out important molecules from waste

Question 20

outline vacuoles

Answer 20

• storage in cells
• in single-celled organisms have a contractile vacuole
• also give young tissue turgor
• store toxic and defense chemicals and ions

Question 21

outline peroxisomes

Answer 21

• oxidative organelles full of H2O2 for detoxification

- they can grow and divide themselves when isolated but bud off the ER too

Question 22

outline glycosomes

Answer 22

-specialised peroxisomes in plant tissue that break down fat reserves in seeds to produce sugars for growins seedlings.

Question 23

what is the endosymbiont theory

Answer 23

the theory that cholorplast and mitochonria derive from ancesteral prokaryotes that became symbiont. this was due to finding mitochondiral and chloroplast DNA mtDNA and ctDNA. they also grow and divide themselves in a cell.

Question 24

outline mitochondria

Answer 24

• use aerobic synthesis of ADP to ATP to produce energy for the cell.
• enclsoing outer membrane
• internal highly folded membrane (the cristae enclosing the matrix)

Question 25

outline chloroplasts

Answer 25

- use photosynthesis to transfer light -> chemical energy to generate ADP/ATP. - 2 enclosing membranes - thylakoid membrane is elaborately folded

Question 26

outline cytoskeleton

Answer 26

- holds orgnaelles in place, gives structure, transport - micro/actin filaments: muscle fibre contraction, cytoplasmic streaming - microtubules: deconstruct fast, act as railways - intermediate filaments -myosin: motor protein which attaches to vesicles fro transport.

Question 27

outline extracellular matrix

Answer 27

-represents cells physically interacting with each other.