1.2 Ultrastructure of Cells

Question 1

Prokaryotes Cell Structure vs. Eukaryotic Cell Structure

Answer 1

Prokaryotes have simpler cell structures and are not compartmentalised compared to eukaryotic cells which are more complex and are compartmentalised (membrane-bound)

Question 2

Electron Microscope vs. Light Microscope

Answer 2

Electron microscopes have a much higher resolution compared to light microscopes
Resolution: ability to distinguish between two different points

Question 3

How do Prokaryotes Reproduce/Divide?

Answer 3

Binary fission: (semi-conservative)

1. The cell replicates its DNA
2. The cytoplasmic membrane elongates, DNA separates (pulled through opposite poles through spindle fibres)
3. Cross wall forms; membrane starts to form
4. Cell wall completely forms
5. Results in to 2 daughter cells

Question 4

Prokaryote Cell Structure

Answer 4

Cell wall, plasma membrane, pili, cytoplasm, nucleoid (naked DNA), ribosomes (70s), flagellum [7 total]

Question 5

Eukaryote Cell Structure (Animal)

Answer 5

Plasma membrane, nucleus, cytoplasm, rough endoplasmic reticulum (RER), mitochondria, golgi apparatus, lysosomes, free ribosomes (80s) [8 total]

Question 6

Eukaryote Cell Structure (Plant)

Answer 6

Plasma membrane, nucleus, cytoplasm, rough endoplasmic reticulum (RER), mitochondria, golgi apparatus, lysosomes, free ribosomes (80s), cell wall, chloroplast, vacuole [11 total]

Question 7

Cell wall

Answer 7

Protective protein-based coating (gram+/gram-)

Question 8

Plasma membrane

Answer 8

Selectively permeable - controls entry and exit of the materials to and from the cell

Question 9

Pili

Answer 9

Allow communication (attach to other bacteria) e.g. DNA transfer, proteins, etc.

Question 10

Cytoplasm

Answer 10

Contains enzymes for metabolic reactions

Question 11

Nucleoid

Answer 11

Closed loop of bacterial DNA in a condensed area (made of nucleotides but doesn’t associate with proteins)

Question 12

Ribosomes

Answer 12

Responsible for protein synthesis - translate the information encoded in messenger RNA (mRNA) into a polypeptide

Question 13

Flagellum

Answer 13

Whiplash-like motion that causes movement

Question 14

Endosymbiotic theory

Answer 14

Smaller unicellular organisms were engulfed and became part of the larger organism eventually evolving into a eukaryote

Shows that eukaryotic cells are more complex than prokaryotic cells

Question 15

Compare/contrast prokaryotic cells and eukaryotic cells

Answer 15

Size: 1-3um vs 10-100um
DNA: closed loop vs double helix
Nucleus: DNA in cytoplasm vs has a nuclear membrane + associated with proteins
Organelles: “cell parts” vs membrane bound
Ribosomes: 70s (small) vs 80s (big)
Mitochondria: no vs yes

Question 16

Mitochondria

Answer 16

Site of respiration - converts sugars into ATP

More mitochondria = more use of energy
e.g. muscle cell has more that skin cell (muscles need more energy bc of movement/contraction/extension vs skin cells that doesn’t move)
STRUCTURE DEPENDS ON FUNCTION

Question 17

Free ribosomes

Answer 17

Produces proteins to be used by the cell

Question 18

Rough endoplasmic reticulum (RER)

Answer 18

Creates proteins to be exported from the cell (continuous with the nucleus membrane)

Question 19

Lysosomes

Answer 19

Contains digestive enzymes for breaking down nutrient molecules and dead cell parts for recycling

Question 20

Golgi apparatus

Answer 20

Modifies and packages proteins produced in the RER to be exported by the cell via exocytosis (vesicles formation)

Question 21

Chloroplast

Answer 21

Contains chlorophyll; site of photosynthesis

Question 22

Vacuole

Answer 22

Storage of materials (water, sugar)