Cells

Question 1

main components of cell:

Answer 1

plasma membrane, nucleus, cytoplasm

Question 2

plasma membrane consists of:

Answer 2

double layer of phospholipids, cholesterol and glycolipids

different embedded proteins (transmembrane? and peripheral) = selective permeability

organelle membranes also have same basic structure

Question 3

plasma membrane function:

Answer 3

physical barrier, regulates molecule movement in/out of cell, mediates cellular recognition/ interaction

Question 4

protein function in plasma membrane:

Answer 4

receptors, enzymes and cell identity markers

Question 5

plasma membrane fluids: (intracellular + extracellular)?

Answer 5

intracellular: cytosol
extracellular: interstitial- plasma and lymph

Question 6

passive movement through membranes:

Answer 6

diffusion: molecules move from high - low conc.

facilitated dif: with aid of membrane carriers

osmosis: H2O molecules move from high - low conc.

Question 7

active movement through membranes:

Answer 7

active transport: carrier mediated transport of solutes (from low - high conc.)

endocytosis:
- Pynocytosis: membrane engulfs fluid from extracellular env.
- Phagocytosis: membrane engulfs solid particles from extracellular env.

exocytosis: releasing molecules from cell = vesicle rupture

Question 8

nucleus structure:

Answer 8

double layered nuclear membrane/ envelope

nuclear pores: selective gates- allow material in/out of nucleus

Question 9

nucleus contents:

Answer 9

contains DNA, encoding instructions for cells, tissues, organs and whole organism

Question 10

nucleolus:

Answer 10

dense sphere in nucleus, produces ribosomes (for protein synthesis)

Question 11

chromatin:

Answer 11

threadlike mass of DNA, proteins and lil RNA

when dividing will coil and thicken into chromosomes

Question 12

define cytoplasm: and contents

Answer 12

part of cell outside nucleus, bound by plasma membrane

has cytosol and organelles

Question 13

cytosol:

Answer 13

fluid portion= water, dissolved solutes, suspended particles (metabolic products- non-moving, non-living components eg. pigment granules, lipid droplets, glycogen)

Question 14

define + list organelles

Answer 14

specialised structures= cell growth, maintenance and reproduction

Cytoskeleton, rER/ sER, Golgi complex, endosomes, lysosomes, vesicles, mitochondria, peroxisomes, centrioles, ribosomes

Question 15

cytoskeleton: structure/ function

Answer 15

cells crisscrossed with fibres of actin, tubilin and other proteins

maintain cell shape

movement of organelles, cell locomotion, muscle fibre contraction

Question 16

cytoskeleton: types

Answer 16

microfilaments (actin, myosin)

intermediate filaments (keratin)

microtubules (tubilin)

Question 17

ribosome location/ composition/ importance:

Answer 17

organelles either free in cytosol or membrane-bound (on rER)

made of protein and RNA molecules

translate mRNA - protein

Question 18

endoplasmic reticulum:

Answer 18

interconnected membranes attached to n. envelope (rER) with minute folds= cisternae

rER: protein synthesis/storage -transported via vesicles

sER: lipid synthesis/storage and detoxification

Question 19

Golgi complex:

Answer 19

membrane + cisternae

complete modifications, sort/package products made by cell, cellular secretion (vesicles) - exocytosis

Question 20

mitochondria:

Answer 20

double membrane organelle- smooth outer + inner cristae/folds

aerobic respiration, converts carbs + oxy -> Co2 + h2o = ATP

holds own DNA, inherited from mother

Question 21

lysosomes: and eg

Answer 21

membrane bound vesicles made from Golgi complex

60+ digestive enzymes act on macromolecules both in/out of cell

leukocyte: large phagocytic lysosomes in white blood cells

Question 22

what is the Tay-Sachs disease?

Answer 22

in healthy child:

• lipid (GM2) ganglioside in nerve cell as food
• enzyme/lysosome Hex-A digests GM2

with disease:

• Hex-A enzyme is not present
• GM2 accumulates and eventually kills cells = shut down nervous system

Question 23

motile features: and 2 eg

Answer 23

made of microtubules, cilia and flagella

Question 24

cilia:

Answer 24

20 microtubules surrounded by plasma membrane

Question 25

flagella:

Answer 25

similar structure, but larger (eg. sperm)

Question 26

what are cell junctions/ eg

Answer 26

contact points between plasma membranes of tissue cells:

• tight junction
• adherens junc.
• desmosomes
• hemidesmosomes
• gap junc.

Question 27

tight junction:

Answer 27

transmembrane proteins = weblike strands fusing neighbouring plasma membranes

Question 28

adherens junction:

Answer 28

adhesion belt/ plaques (thick layer of proteins attached to microfilaments and membrane proteins) joined by cadherins (transmembrane glycoprotein)

Question 29

desmosomes:

Answer 29

plaques of intermediate filaments and cadherins

Question 30

hemidesmosomes:

Answer 30

half of desmosome:

anchor cells to basement membrane, using integrin instead of cadherins

Question 31

gap junction:

Answer 31

connexins (membrane protein) creating connexons (tunnels) between cells

intercellular space in between adjacent cells