Cell theory

Question 1

Cytoplasm

Answer 1

• Organnelles
• Cytosol - solution of salts, sugars, amino acids, fatty acids, nucleotides, vitamins, minerals, enzymes and dissolved gases

Question 2

Nucleus

Answer 2

nuclear envelope —> nucleolus + chromatin + karyolymph
- skeletal muscles can have more than 1
- can be lost during maturation e.g. red blood cells
- spherical

Question 3

Chromatin

Answer 3

DNA + proteins (histones)

Question 4

Nucleolus

Answer 4

• takes part in ribosome synthesis
• DNA + ribosomal RNA

Question 5

Mitochondria

Answer 5

• double membrane
• inner membrane invaginated (cristae)
• matrix - liquid component with respiratory enzymes, ribosomes, circular DNA
• DNA replication is independent from nuclear

Question 6

Rough endoplasmic reticulum

Answer 6

Consists of flattened membrane sheets (cisternae) with membrane-bound ribosomes, near the nucleus
- protein synthesis and transport towards the Golgi apparatus —> exporting proteins out
- protein folding and modification

Question 7

Smooth endoplasmic reticulum

Answer 7

Tubular membranes, usually farther from the nucleus than RER, sarcoplasmic reticulum in muscles (Ca ion concentration)
- lipid synthesis (phospholipids, cholesterol)
- detoxification of harmful metabolic byproducts

Question 8

Ribosomes

Answer 8

80s / 70s, protein + rRNA (no membrane)
- enzymatic machinery for protein synthesis
- may be membrane bounded

Question 9

Golgi bodies

Answer 9

flattened membranes called cisternae, system of associated vesicles (divided sacks),
- processing proteins
- glycolipid synthesis
- condensation of substances and preparing them for secretion in form of vesicles (endocytosis/ exocytosis)

Question 10

Lysosomes

Answer 10

Contains hydrolysis enzymes in animal cells, vesicles that stay within the cytoplasm
- digestive enzymes to break down food

Question 11

Microbodies / cytosomes

Answer 11

single membrane, plant cells, contain oxidative enzymes and detoxifies

Question 12

Cytoskeleton

Answer 12

microtubules, intermediate fillaments, microfilaments (actine-spectrin forming 3D nets)
- maintaining physical structure
- movement

Question 13

Microtubules

Answer 13

Centriole (organisation of microtubules), help form Cilia and Flagella

Question 14

Cell surface membrane

Answer 14

phospholipid bilayer, peripheral proteins, cholesterol, integral proteins, glycoprotein
- cellular control
- homeostasis (enter <—> leave)

Question 15

Cell differentiation

Answer 15

expression of some genes (active genes) and not others in a cells genome (selective gene expression), cell becomes specialised in structure and function

Question 16

Exocytosis

Answer 16

Large molecule —> out of the cell, vesicle fuses with cell membrane

Question 17

Diffusion

Answer 17

Higher concentration —> lower (ions, molecules, etc.)

Question 18

Vacuole

Answer 18

• stores water in plants, large, permanent - Central vacuole
• small in animal cells

Question 19

Cell wall

Answer 19

100s of strands of cellulose
Gives strength, shape to plants, creates internal pressure (turgor pressure)
Internal transport - apoplast pathway, water moves through the Xylem

Question 20

Tubulin

Answer 20

globular proteins that form filaments —> microtubules, eukaryotic cytoskeleton

Question 21

Cell theory

Answer 21

cells are the smallest unit of life, unicellular and multicellular organisms, all cells come from pre-existing cells

Question 22

Cell origin: what is needed?

Answer 22

• molecules must be present (organic)
• enzyme - catalysts
• vesicle formation - compartmentalisation
• RNA - uncomplex

Question 23

Miller & Urey experiment

Answer 23

1. Earth - sea water + atmosphere (NH3, CH4, H2) + lightning
2. Heated H2O —> reacted with ‚atmosphere’ and sparks
3. Primordial soup - amino acids + hydrocarbons

Question 24

Introns

Answer 24

Non-coding sections of an RNA transcript, nucleotide sequence that is not expressed

Question 25

Nitrogen fixation

Answer 25

Azotobacter - free-living , N2 —> NH3, necessary for the nitrogen cycle and soil fertility

Question 26

Single membrane-bound organelles

Answer 26

Golgi apparatus, Endoplasmic reticulum, Vacuole, Lysosome

Question 27

Double membrane-bound organelles

Answer 27

Nucleus, mitochondria and chloroplasts

Question 28

Osmosis

Answer 28

Movement of water molecules from lower solute concentration to higher hypotonic —> hypertonic Isotonic - same osmolarity

Question 29

Interphase

Answer 29

G1 - growth, normal metabolic rates S - synthesis of DNA G2 - growth stops, preparation for division

Question 30

Prophase

Answer 30

- Nuclear membrane breaks - DNA supercoils creating chromosomes - paired centrosomes —> opp poles

Question 31

Metaphase

Answer 31

- microtubules attach to centromeres - chromosomes align across the equator of the cell - microtubules depolymerisation

Question 32

Anaphase

Answer 32

- sister chromatids seperate, cohesin loops are cut - opp poles

Question 33

Telophase

Answer 33

- spindle fibres dissolve - chromosomes decondense - nucleus reforms - plant cells - carbohydrate rich vesicles align at the equatorial plate, fuse

Question 34

Cytokinesis

Answer 34

- cleavage furrow —> contractile ring / cell plate fuses with the cell wall

Question 35

Meiosis 1

Answer 35

Prophase 1 - chromosomes align with a homologous pair, crossing over Meta Ana 1 - sister chromatids stay together Telo 1 - each cell has non-identical sister chromatids 2 haploid cells

Question 36

Meiosis 2

Answer 36

- centrosomes duplicated between 1 and 2 - mitosis creating haploid cells

Question 37

Oogenesis

Answer 37

Meiosis 1 Meiosis 2 Ovum + 3 polar bodies