Lecture 5: Cell Structure

Question 1

all cells have the four following (describe their function too):

Answer 1

• plasma membrane: selectively permeable barrier
• nucleic acid: store, transmit, and process info
• proteins: perform cell functions
• carbohydrates: provide chemical energy, carbon, suport, and identity (cell markers)

Question 2

prokaryotes vs eukaryotes

Answer 2

• prokaryotes: unicellular organism with no nucleus/ other membrane bound organelles (bacteria or archaea)
• eukaryotes: have nucleus , mitochondria, and other organelles

Question 3

archaea

Answer 3

• genetically and biochemically different from bacteria; organism that lives in extreme environments

Question 4

Fill in the blank and answer: animal and plant cells are ___ _______ than bacteria. What are the advantages of small cells and advantages of large cells?

Answer 4

• ~10x larger
• small cells advantage: large SA:V ratio; faster exchange in/ out of cell. shorter transport distance
• large cells advantage: more space, more storage, more compartments

Question 5

prokaryotic cells

• explain walls
• size
• surrounded by what
• inside: cytoplasm (4)

Answer 5

• protective cell walls made of amino acid/ sugar polymer (peptidoglycan)
• 1-10um
• cells are surrounded by a membrane
• inside: chromosomes (condensed DNA), plasmids (auxillary DNA), ribosomes (for protein synthesis), intracellular fluid aka cytosol (made of proteins, ions, metabolites, etc)

Question 6

eukaryotic cells

• size
• compartmentalized

Answer 6

• 5-100um

- compartmentalised: nucleus and other organelles surrounded by membrane in the cytoplasm

Question 7

what are the advantages of having compartments within a cell?

Answer 7

• allows for more specialization (and more functions)
• you can separate incompatible chemical reactions
• smaller units with more concentrated content

Question 8

can you identify the organelles in the google doc?

Answer 8

• see google doc

Question 9

nucleus

• how many membranes
• function
• nucleolus
• nuclear lamina

Answer 9

• double membrane with pores (nuclear envelope)
• contain DNA in chromosomes
• nucleolus makes RNA
• nuclear lamina: lattice structure for support

Question 10

endoplasmic reticulum

• structure/shape (made from what?)
• rough ER
• smooth ER
• lumen

Answer 10

• nuclear envelope extends into cytoplasm for the sac-like organelle
• rough: studded with ribosomes; site of protein synthesis and folding
• smooth: extends further into cell and site of membrane lipid synthesis and assembly of membrane (lipid processing centre)
• lumen: inside space in the ER

Question 11

golgi apparatus

• structure
• function
• cisterna
• trans vs cis golgi

Answer 11

• stacks of flat sacs and free vesicles
• site of protein modifications (process, sort, ship)
• cisterna: flattened membrane discs that make up the golgi apparatus stacks
• proteins move from the ER to the plasma membrane side (trans golgi)
• cis golgi: nuclear side

Question 12

lysosome

• function
• hydrolases
• hydrolysis

Answer 12

• aka recycling centre where proteins, lipids, carbs, and nucleic acids are all broken down into compartments (amino acids, fatty acids, sugars, nucleotides)
• hydrolases: digestive enzymes
• hydrolysis: occurs in lysosome when material is digested; breakdown of compound due to reaction with water

Question 13

endomembrane system

- key players (3)

Answer 13

• although they’re separate, they’re connected by the system

- content moves along in vesicles through (see notes)

Question 14

peroxisomes

• structure
• origin
• function

Answer 14

• membrane enclosed structures that originate from ER vesicle
• break down some lipids and other components by oxidation
• oxidation results in production of hydrogen peroxide as a by product (toxic)
• peroxisomes protect cell against H2O2 through compartmentalization; catalase breaks down H2O2

Question 15

mitochondria

• membrane
• cristae
• mitochondrial matrix
• function
• has their own?

Answer 15

• double membrane
• folded saclike structure that extends inward to increase SA (cristae); area between cristae called mitochondrial matrix
• powerhouse of the cell
• produce ATP
• have their own DNA that encode of their protein but most are imported

Question 16

plant cells are similar to animal cells except (3):

Answer 16

• cell wall
• lysosomes are replaced by vacuoles
• have chloroplasts where photosynthesis occurs

Question 17

vacuoles

• function
• in seeds: ___
• in flower: __
• many contain:

Answer 17

• storage centre
• in seeds: store nutrients for germination
• in flowers: store pigments
• many contain toxic components for defence (caffeine, nicotine, THC)

Question 18

chloroplasts

• function
• how many membranes
• grana
• stroma

Answer 18

• photosynthesis
• 3 membranes (outer, inner, thylakoid membrane)
• grana: thylakoid stacks
• stroma: space between inner + thylakoid membrane