The Cell

Question 1

The plasma membrane

Answer 1

Forms a cells flexible outer surface and separates the cell’s internal environment from its external environment.
It regulates the flow of material into and out of the cell.
Plays a key role in communication between cells and with their external environment

Question 2

Framework of the plasma membrane

Answer 2

lipid bilayer - two tail to tail layers made up of three types of lipid molecules: phospholipids, cholesterol and glycolipids

Question 3

Integral protein in plasma membrane

Answer 3

extends through lipid bilayer and allows small and medium water soluble materials to cross the membrane

Question 4

Peripheral protein in plasma membrane

Answer 4

loosely attached to exterior or interior surface of the membrane

Question 5

Name of fluid in body cells

Answer 5

Intracellular fluid - 2/3 of the total fluid in our bodies

Question 6

ICF

Answer 6

intracellular fluid - found in body cells

Question 7

ECF

Answer 7

extracellular fluid - found outside cells

Question 8

Interstitial fluid

Answer 8

ECF between cells in tissues

Question 9

Blood plasma

Answer 9

ECF in blood vessels

Question 10

Lymph

Answer 10

ECF in lymphatic vessels

Question 11

CSF

Answer 11

cerebrospinal fluid- surrounds brain and spinal cord

Question 12

Solute

Answer 12

any material dissolved in fluid

Question 13

Solvent

Answer 13

fluid that dissolves materials

Question 14

How much fluid is in our bodies?

Answer 14

8 pints or 4 litres

Question 15

How permeable is the plasma membrane?

Answer 15

Selectively permeable - allows some substances but restricts the access of others

Question 16

What is the lipid bilayer permeable to?

Answer 16

water and non polar molecules

Question 17

Macrophages

Answer 17

eat anything that’s foreign - when they are overwhelmed, it causes glands to swell up

Question 18

Passive processes

Answer 18

substance moves down its concentration gradient through the membrane, using only its own energy of motion.
Includes simple diffusion and osmosis

Question 19

Active processes

Answer 19

cellular energy is used to push the substance through the membrane ‘uphill’ against its concentration gradient
e.g. active transport

Question 20

Brownian motion

Answer 20

moving from an area of high concentration to an area of low concentration

Question 21

Simple diffusion

Answer 21

when substances move across a membrane through the lipid bilayer e.g. fatty acids, steroids, O2, CO2

Question 22

Facilitated diffusion

Answer 22

when substances that can’t move through the lipid bilayer by simple diffusion cross the plasma membrane by a passive process.
An integral membrane protein (a channel or a carrier) assists a specific substance to move across the membrane.

Question 23

How do channel proteins open?

Answer 23

By a flow of electricity - they get excited

Question 24

Osmosis

Answer 24

a net movement of water through a permeable membrane. high concentration –> low concentration

Question 25

Phagocytosis

Answer 25

'cell eating'. Large, solid particles such as bacteria are taken in by the cell

Question 26

Bulk phase endocytosis

Answer 26

'cell drinking'. Cells take up tiny droplets of extracellular fluid

Question 27

Exocytosis

Answer 27

results in secretion or the liberation of materials out of a cell

Question 28

Cytoplasm

Answer 28

The structural framework for the cell which generates movement. Cytosol is the liquid portion of the cytoplasm that surrounds organelles - 55% of total cell volume. Composed of three different types of protein filaments - microfilaments, intermediate filaments and microtubules

Question 29

Ribosomes

Answer 29

Ribosomes are the site of protein synthesis. Have a high content of RNA.

Question 30

ER

Answer 30

Endoplasmic Reticulum - network of folded membrane of flattened tubules

Question 31

Rough ER

Answer 31

extends from nuclear envelope and is studded with ribosomes. Function is to synthesise proteins

Question 32

Smooth ER

Answer 32

extends from rough ER and lacks ribosomes. Fatty acids and steroids such as estrogens and testosterones are synthesised

Question 33

Golgi complex

Answer 33

After proteins are synthesised on a ribosome attached to ER, most are transported to another region of the cell. First step of transport pathways is the golgi complex whose main function is to modify and package proteins. They are then sorted and packaged into vesicles

Question 34

Mitochondria

Answer 34

site of most ATP production. A series of inner folds called mitochondrial cristae and a larg central fluid filled cavity is the mitochondrial matrix ATP (3 phosphates) ADP (2 phosphates)

Question 35

Nucelus

Answer 35

spherical or oval structure. A double membrane called the nuclear envelope separates the nucleus and cytoplasm. Nuclear pores pierce the envelope and control the movement of substances between the nucleus and cytoplasm. Contains DNA which allows replication of cells

Question 36

Nucleoli

Answer 36

Inside nucleus. Clusters of protein, DNA and RNA which are the sites of the assembly of ribosomes

Question 37

Genes

Answer 37

Within nucleus and control cellular structure and direct most cellular activities. Arranged along chemical chromosomes.

Question 38

Protein Synthesis

Answer 38

Information contained in DNA is transcribed to produce a complementary sequence of codons in a strand of RNA. This is catalysed by enzyme RNA polymerase. RNA then attaches to a ribosome, where the information in RNA is translated into specific amino acids to form a new protein molecule.

Question 39

How much ATP does the body produce?

Answer 39

Total ATP in an adult is approximately 0.1mol/L. We require 100-150mol/L daily so each ATP molecule is recyled 1000-1500 times per day.

Question 40

Glycolysis

Answer 40

reactions that extract energy from glucose by splitting it into two 3-carbon molecules

Question 41

Two main phases of the glycolytic pathway

Answer 41

Energy requiring phase - starting molecule of glucose is rearranged and two phosphate groups are attached. The phosphate groups make the fructose-1,6-biphosphate, which is unstable so it splits in half to form two phosphate bearing three carbon sugars. Two ATP molecules are used. Energy releasing phase - each three carbon sugar is converted to another three carbon molecule, pyruvate, through a series of reactions. Two ATP molecules and one NADH molecule produced, but process is repeated twice for two of the carbon sugars so four ATP molecules and two NADH molecules produced overall.