Chapter 4 - Cell Structure and Function

Question 1

What components are present in all cells?

Answer 1

• plasma membrane
• cytoplasm
• nucleus (eukaryotic)
• nucleoid (prokaryotic)

Question 2

Plasma membrane

Answer 2

Selective barrier between cell contents and the environment

Question 3

Lipid bilayer

Answer 3

• controls the flow of substances across it
• consists of mainly phospholipids
• separates cell contents from surrounding environment

Question 4

Selectively permeable

Answer 4

Allows the passage of certain molecules/ions while keeping the other substances out

Question 5

Fluid mosaic model

Answer 5

Describes the structure of the plasma membrane as a mosaic of components

Question 6

Hydrophilic

Answer 6

• water loving

- polar heads on the inner and outer surfaces of the membrane

Question 7

Hydrophobic

Answer 7

• water fearing

- non polar tails form the center of the membrane

Question 8

Adhesion

Answer 8

Holds cells together or to external proteins

Question 9

Enzymes

Answer 9

Speed reactions at membrane

Question 10

Receptors

Answer 10

Trigger a change in cellular activity and response to a stimulus

Question 11

Transport as channels/carriers

Answer 11

Move or allow specific substances across lipid bilayer

Question 12

Cell wall

Answer 12

• rigid, permeable structure

- ions and other solutes can cross easily

Question 13

Capsule

Answer 13

• help cells adhere to many types of surfaces

- protect cells against predators and toxins

Question 14

Nucleoid

Answer 14

Region of cytoplasm where the DNA is concentrated

Question 15

Plasmid

Answer 15

Carries genes that provide advantages such as resistance to antibiotics

Question 16

Flagella

Answer 16

Used for motility

Question 17

Pili

Answer 17

• protein filaments used for attachment

- “sex” pilus transfers genetic material via conjugation

Question 18

Nucleus

Answer 18

Contains DNA

Question 19

Cytoplasm

Answer 19

Semi-fluid substance enclosed by a cell’s plasma membrane

Question 20

Cytosol

Answer 20

The fluid component of cytoplasm

Question 21

Nuclear envelope

Answer 21

A double membrane that constitutes the outer boundary of the nucleus

Question 22

Nucleoplasm

Answer 22

Viscous fluid enclosed by the nuclear envelope

Question 23

Nucleolus

Answer 23

Dense, irregularly shaped region where ribosomal subunits are assembled

Question 24

The endomembrane system

Answer 24

A multifunctional network of interconnected, membrane-enclosed organelles

Question 25

Organelles

Answer 25

Work together to modify, package, and transport lipids and proteins

Question 26

Endoplasmic reticulum (ER)

Answer 26

Tubes/sacs extending from the nuclear envelope

Question 27

Rough endoplasmic reticulum (rough ER)

Answer 27

- studded with ribosomes | - synthesizes proteins

Question 28

Smooth endoplasmic reticulum (ER)

Answer 28

- lacks ribosomes - functions in lipid synthesis and metabolism - detoxification of drugs and pesticides - storage of calcium ions

Question 29

Golgi bodies (golgi apparatus)

Answer 29

- further modify proteins and lipids delivered from ER | - sort and package finished products into vesicles

Question 30

Vesicles

Answer 30

Formed naturally during the processes of secretion, uptake, and transport of materials within the cytoplasm

Question 31

Peroxisomes

Answer 31

- digest fatty acids and amino acids | - break down toxins and metabolic by-products

Question 32

Lysosomes

Answer 32

Break down cellular waste and debris

Question 33

Vacuole

Answer 33

- large, fluid-filled vesicles | - store and break down waste, debris, toxins or food

Question 34

Central vacuole (plants)

Answer 34

- storage in many plant cells | - fluid pressure keeps plant cells plump and firm

Question 35

Mitochondria

Answer 35

- site of ATP synthesis - have double membrane - have their own DNA and ribosomes - replicate independently from the cell

Question 36

Plastids

Answer 36

Photosynthesis, pigmentation, storage in plants and algae cells

Question 37

Chloroplasts

Answer 37

- specialised in photosynthesis | - contain chlorophyll

Question 38

Chlorophyll

Answer 38

Green pigment that traps light energy for photosynthesis

Question 39

Chloroplast structure

Answer 39

- disc-shaped or oval | - have own DNA

Question 40

Chromoplasts

Answer 40

- make and store pigments other than chlorophyll | - eg: color change during fruit ripening

Question 41

Amyloplasts

Answer 41

- unpigmented | - make and store starch grains

Question 42

Cytoskeleton

Answer 42

Dynamic framework of protein filaments that support, organise, and move eukaryotic cells and their internal structures

Question 43

Functions of cytoskeleton

Answer 43

- maintain cell shape and internal organisation - moves cell structure - provides machinery for intracellular transport - enables cells to carry out essential functions such as division

Question 44

Microtubules

Answer 44

- tubulin subunits | - involved in moving cell parts

Question 45

Microfilaments

Answer 45

- subunits: protein actin - reinforces cell membrane- change or strengthen the shape of a cell - cell movement, contraction and migration

Question 46

Intermediate filaments

Answer 46

- fibrous subunits - most stable - provide mechanical strength and help stabilise cell shape

Question 47

Cellular movement

Answer 47

- motor protein interacts with cytoskeletal elements to move cell parts or the whole cell - uses energy ATP

Question 48

Centrosomes

Answer 48

Act as the major microtubule organising centres in animal cells