Ch 2: Cells

Question 1

What is life?

Answer 1

1. Response to the environment
2. Exchange of materials with the environment
3. Metabolism
4. Growth
5. Reproduction

Cell is first fundamental sign of life.

Virus is not alive

Question 2

Prokaryotic cells

Answer 2

• No true nucleus
• 1 to 10 µm
• ex: bacteria

Question 3

Eukaryotic cells

Answer 3

• Have a true nucleus
• 10 to 100 µm (1/100 to 1/10 mm)
• almost all other cells that are not bacteria

Question 4

Unicellular

Answer 4

• Each cell carries out all life processes
• Usually found in clusters
• Bacteria are unicellular

Question 5

Multicellular

Answer 5

Made up of many cells, with different cells specialized to perform different functions

Question 6

Why are cells so small?

Answer 6

Cells are small because they require a high surface to volume ratio to exchange materials with their environment.

Question 7

Bacterial cells

Answer 7

• Prokaryotic
• no true nucleus
• no endoplasmic reticulum
• no Golgi apparatus
• no mitochondria
• no chloroplasts
• no vesicles or vacuoles
• no centrosome

Question 8

Bacterial cell anatomy: Cytosol

Answer 8

• Mixture of enzymes and many other molecules in water.
• Many chemical reactions take place in the cytosol.

Question 9

Bacterial cell anatomy: Flagellum

Answer 9

• Hair-like
• Attaches at plasma
• Rotates to provide mobility
• Not all bacteria have it

Question 10

Bacterial cell anatomy: Thylakoid

Answer 10

Provides a membrane for photosynthesis

Not all bacteria have this

Question 11

Bacterial cell anatomy: Capsule

Answer 11

• Not all bacteria have this
• Thick, sticky, gooey layer
• Protects the cell from attack or dehydration
• Allows some cells to stick together
• When bacteria with a capsule infect you, your immune system doesn’t recognize them/kill them.

Question 12

Bacterial cell anatomy: Plasmid

Answer 12

• Not all bacterial cells have this
• Accessory genetic information
• Bacteria can trade these
• Scientists can use it to add extra genes for our purposes

Question 13

Bacterial cell anatomy: Cell wall

Answer 13

• NOT a fluid like the plasma membrane
• Relatively rigid (gives the cell its shape)
• Prevents it from bursting
• Porous
• Most bacteria (not all) have this

Question 14

Bacterial cell anatomy: Plasma Membrane

Answer 14

• AKA cell membrane
• Boundary between cell and environment.
• Controls movement of material in and out (exchange)
• Made of a phospholipid bilayer

Question 15

Plasma membrane: Phospholipid bilayer

Answer 15

• Made of lipid molecules that have a polar head and non-polar tails.
• In water, the tails go in towards the center and the heads form two layers surrounding the tails because the heads like water but not the tails (semi-permeable)
• This bilayer is actually a fluid (not solid)
• The non-polar layer makes it relatively non-permeable to polar molecules.
• The non-polar molecules pass through easily (CO₂ , O₂ , lipids, …). They diffuse through freely.
• Some small polar molecules can actually sneak in, but very slowly.
• Larger polar molecules (ex: glucose) and ions diffuse through hardly at all, but there are some proteins embedded in the bilayer that will let some of the important stuff in.

Question 16

Facilitated Diffusion (plasma membrane)

Answer 16

1. Channel protein: Very specific about what it lets in. No control over in-out direction. Aquaporins (water channels)
2. Gated channel proteins: Gates open or close depending on what the cell needs (or other various events)
3. Carrier protein: only allows in a specific, but larger molecule.

• All 3 of these help with facilitated diffusion or passive transport (diffusion to areas of smaller concentration)

Question 17

Active transport protein

Answer 17

• Also for transport in or out of the cell, but not by diffusion (it can bring something in even in concentration is higher inside)
• The cell provides energy to this protein which transports specific molecules in or out of the cell

Question 18

Animal cells

Answer 18

• no cell wall
• no plasmodesmata
• no chloroplasts
• no central vacuole
• DNA is not in a loop like in prokaryotic cells

Question 19

Eukaryotic Cell Anatomy (Animal)

Answer 19

Question 20

Animal Cell Anatomy

Better View of the Cytoskeleton

Answer 20

• Centrosome: Contains centrioles. With pair of centrioles, the centrosome organizes the cytoskeleton
• Cytoskeleton: Gives the cell its shape, allows cell to change its shape, helps with intracellular transport

Question 21

Eukaryotic Cell Anatomy (Animal)

Plasma Membrane

Answer 21

• Phospholipid bilayer
• Tight junction protein: helps cells stick together
• Extracellular matrix: strengthens tissues, helps cells to react to the environment (with glycoproteins like glycogen)
• Cholesterol: helps maintain membrane fluidity. Non-polar
• Protein receptor: allows cells to respond to only specific chemicals

Question 22

Eukaryotic Cell Anatomy

Animal

Cytosol

Answer 22

• Synthesis of proteins that need to be packaged

Question 23

Eukaryotic Cell Anatomy

Animal

Cilium

Answer 23

• Coordinated beating to provide mobility

Question 24

Eukaryotic Cell Anatomy

Animal

Flagellum

Answer 24

• Unlike in prokaryotic cells, these whip instead of rotate to provide mobility

Question 25

Eukaryotic Cell Anatomy MITOCHONDRION (Animal)

Answer 25

* Generates ATP for the cell * Have several features that are similar to a prokaryotic cell 1. Outer Membrane: similar to the plasma membrane 2. Inner Membrane: similar to a prokaryotic plasma membrane 3. Loop of DNA 4. Ribosomes: Similar to prokaryotic ribosomes 5. Matrix: Fluid, similar to cytosol

Question 26

Eukaryotic Cell Anatomy Animal Nucleus

Answer 26

* Nucleus contains the nucleolus, chromatin and nuclear envelope * Definining feature of the eukaryotic cell 1. Nucleolus: Site of assembly of ribosomes 2. Nuclear envelope: Double membrane 3. Chromatin: Substance holding most of the genetic information. Made of several diffuse chromosomes (each made of one double-stranded DNA molecule with associated proteins)

Question 27

Eukaryotic Cell Anatomy Animal Smooth endoplasmic reticulum

Answer 27

* Synthesis of lipids * Destruction of drugs and toxins (we have many in our liver)

Question 28

Eukaryotic Cell Anatomy Animal Rough Endoplasmic Reticulum

Answer 28

* Synthesis of proteins that need to be packaged (i.e. needed in the blood to signal, but not needed in the cell. ex: insulin) * Looks rough under a microscope because it's covered in ribosomes

Question 29

Eukaryotic Cell Anatomy Animal Ribosomes

Answer 29

* Protein synthesis

Question 30

Eukaryotic Cell Anatomy Animal Vacuole

Answer 30

* Larger membrane sack of material * Several types: Lysosome (vacuole of digestive enzymes

Question 31

Eukaryotic Cell Anatomy Animal Vesicle

Answer 31

* Small membrane sack of material * Small packages that pinched off the rough ER * Composed of a phospholipid biliayer * Package will go join the Golgi Apparatus

Question 32

Eukaryotic Cell Anatomy Animal Golgi Apparatus

Answer 32

* Phospholipid bilayer * Package, modify and sort proteins from Rought E.R.

Question 33

Plant cells

Answer 33

* no centrosome * no lysosomes * cell wall: cellulose. Cell walls are NOT present in animal cells. * Cytoskeleton, but no centrosome. The nuclear envelope organises part of the cytoskeleton. * Chloroplasts (site of photosynthesis in plants) * Large central vacuole (storage, turgor (stiffness caused by water pressure)). Animal cells tend to have many small ones instead. * Plasmodesmata: channel that allows connection between cells. Allows cytosol and other material to move from cell to cell.

Question 34

Plant cells: Chloroplast

Answer 34

* Contains a loop of DNA * Thylakoid: provides a membrane for photosynthesis * Stroma * Inner membrane (phospholipid bilayer) * Outer membrane * Ribosome

Question 35

Fungal cells

Answer 35

* eukaryotic * cell wall: chitin * pores between cells * no plasmodesmata * no centrosome * no chloroplasts

Question 36

Cytosis

Answer 36

Transport via folding of a membrane 1. Endocytosis: Entering the cell by cytosis 2. Exocytosis: Exiting the cell by cytosis

Question 37

What is different about a Bacterial Cell?

Answer 37

1. no true nucleus 2. no endoplasmic reticulum 3. no golgi apparatus 4. no mitochondria 5. no chloroplasts 6. no vesicles or vacuoles 7. (basically no organelles) 8. no centrosome

Question 38

What is different about an Animal Cell?

Answer 38

1. No cell walls 2. No plasmodesmata 3. No chloroplasts 4. No central vacuole (only a bunch of little ones)

Question 39

What is different about plant cells?

Answer 39

1. No centrosome 2. No lysosomes 3. Cell wall is made of cellulose (chemically different than the wall of a bacteria. Cellulose = polusaccharide

Question 40

What is different about Fungal Cells?

Answer 40

1. Eukaryotic 2. Cell wall: chitin 3. No plasmodesmata 4. Pores between cells (large) 5. No centrosome 6. No chloroplasts