Cell Structure and Function (Week 1)

Question 1

What is a cell and what can they do?

Answer 1

• smallest living unit
• individual cells can: grow, reproduce, process info, respond to stimuli, communicate, have chemical reactions, have hereditary material
• they are surrounded by plasma membrane
• RNA viruses use reverse transcription

Question 2

What is cell theory? (4 main ideas)

Answer 2

1) All organisms are made up of one or plus cells that come from pre-existing cells
2) Vital functions of an organism occur in cells
3) Cells have hereditary info important for cell function regulation
4) Genetic info is transmitted to next generation of cells (ie DNA is passed on)

Question 3

Can humans see cells unaided?

Answer 3

Some; the smallest that can be seen unaided are 0.1mm long like ameobas, human eggs and paramecium. Most are seen under light microscope or electron microscope

Question 4

Give examples of microorganisms

Answer 4

Microorganisms: single celled organisms

-bacteria, archea, fungi like yeast

Question 5

What are the 3 domains?

Answer 5

Bacteria, archaea, and eukarya

Question 6

What is the difference between multi celled organisms and single celled organisms?

Answer 6

-multi celled have a higher degree of organization within the organism and have specialization (many can make up tissues)

Question 7

Compare Prokaryotes and Eukaryotes (differences)

Answer 7

Prokayrotes: don’t have membrane bound organelles, have nucleoid (region in prokaryotes containing genetic material), often very simple
Eukaryotes: have membrane bound organelles (nucleus, mitochondria etc), more complex

Question 8

Describe domain bacteria

Answer 8

• single celled
• no organelles or nucleus
• have cell walls made of peptidoglycan
• reproduce using binary fission
• can use organic or inorganic chemicals for energy or can photosynthesize (cyanobacteria)

Question 9

Describe domain archaea

Answer 9

-believed to have common ancestor that gave rise to euarkyotes and diverged them from bacteria
-unicellular
-lack peptidoglycan in cell walls
-live in extreme environments (high salt, high acid, high heat, high methane content etc)
-

Question 10

Compare Prokaryotic Cells and Eukaryotic cells

Answer 10

Prokaryotic cells: use plasmids (circular DNA) and certain bacteria can fix nitrogen
Eukaryotes: DNA bound in nucleus
BOTH: have ribosomes, and a plasma membrane, RNA and DNA

Question 11

Which organisms have cells walls? (in terms of prokaryotes, eukaryotes, and archaea) What is found in each cell wall?

Answer 11

• plants (mostly cellulose), bacteria (peptidoglycan), fungi (chitin), algae and some archaea (pseudopeptidoglycan have cell walls
• animals and protozoa DO NOT have cell walls

Question 12

What is the cytoplasm composed of?

Answer 12

-cytoplasm is composed of interconnected filaments and fibers (microtubules and microfilament, and intermediate filament) as well as fluid or cytosol

Question 13

What kind of storage substances are in the cytoplasm?

Answer 13

-along with organelles calcium oxalateor silicon dioxidein plants, and energy-storage materials like glycogen or lipid droplets

Question 14

What is the ER and what does it do (both smooth and rough)?

Answer 14

-ER is a network of interconnected membranes, comprising tubules and flattened sacs that help move substances within cells
-Two regions of the ER that differ in both
structure and function.
1)Smooth ER acts as a storage organelle & is important in the creation and storage of lipids and steroids.
2) Rough ER (has ribosomes attached to it) helps in the synthesis and packaging of proteins. It’s also attached to the nuclear envelope that surrounds the nucleus. This direct connection helps for the movement of molecules through both membranes.

Question 15

What is the Golgi Apparatus and what does it do?

Answer 15

• The golgi packages proteins inside the cell before they are sent to their destination
• It’s also important in the processing of proteins forsecretion and plays a major part in the endomembrane system

Question 16

What are lysosomes and what do they do?

Answer 16

-Lysosomes digest excess or worn-out organelles, food particles, and engulfviruses or bacteria.
-membrane around lysosome allows the
digestive enzymes to work at the 5 pH needed
- nicknamed “suicide-bags” or “suicide-sacs” due to their autolysis (destruction of cells or tissues by their own enzymes)

Question 17

What are vacuoles and what do they do?

Answer 17

• Vacuoles are membrane bound storage sacs
• they have no basic shape or size, and its structure varies according to the needs of the cell.
• more common in plants than animals
• Contains: water, food and waste
• plant cells have one large central vacuole, while animals have smaller vacuoles often in larger numbers (some have none)

Question 18

What is a tonoplast?

Answer 18

• A tonoplast is membrane that bounds the chief vacuole of a plant cell.
• separates the vacuolar contents from the cell’s cytoplasm.
• Mainly involved in regulating the movements of ions around the cell, and help isolate materials that might be harmful to the cell.

Question 19

Where are microtubules made?

Answer 19

• made in centrosomes

- in animal cell centrosomes, there are small organelles called centrioles

Question 20

Which two organelles are likely of bacterial descent?

Answer 20

• mitochondria (releases energy)

- chloroplasts (store energy; Derived form photosynthetic bacteria)

Question 21

What is the mitochondria and its function?

Answer 21

-membrane (double)-enclosed organelle found in most eukaryotic cells
-they generate most of the cell’s supply ofATP
Alsoinvolved in:
cell signaling
cellular differentiation
cell death
control of the cell cycle
cell growth

Question 22

What is the chloroplast and its function?

Answer 22

-chloroplasts are a type ofplastidspecialized in
photosynthesis via solar energy
-found inplant cellsand some othereukaryotic
organisms
-they also: Photosynthesis, are important for fatty acid synthesis in plants and are involved in a plant’simmune response

Question 23

What is important about the nucleus in euaryotes?

Answer 23

• nucleus is is membrane bound having a nuclear envelope with two membranes; structure is filled with nucleoplasm
• has pores
• centre regulates/controls activities of cell via gene expression; also contains chromosome
• also includes nucleolus where ribosomal RNA sythesis and ribsomes are assembled
• genetic info is folded into a nucleoid for bacterial or achaeal cells and is attached to cell membrane

Question 24

What is DNA?

Answer 24

• DNA is the hereditary material of the cell
• often compacted into chromosomes
• important for the making of proteins and is duplicated before cell division

Question 25

What is the nucleolus?

Answer 25

• non-membrane bound structure found in nucleus; most cells have 2 or more
• helps directs synthesis of RNA and asssembly ofribosomes
• After ribosomes are produced in the nucleolus, they are exported to the cytoplasm where will translate mRNA