Cells and Organelles

Question 1

What is a cell?

Answer 1

A semi-independent living unit used for metabolism, growth and replication

Question 2

What is an organelle?

Answer 2

Subunits within cells that perform special activities

Question 3

What are tissues?

Answer 3

An assembly of cells that carry out similar activities

Question 4

What are organs?

Answer 4

Assemblies of tissues that perform specific functions

Question 5

What are organ systems?

Answer 5

Assemblies of organs with specific related activites

Question 6

What are Prokaryotes?

Answer 6

Single celled organisms with circular DNA and no membranous organelles

Question 7

What are Eukaryotes?

Answer 7

Multicellular organelles with linear DNA chromosomes enclosed in a nucleus with membrane bound organelles

Question 8

What are Viruses?

Answer 8

An assembly of nucleic acid proteins. They invade cells and use their machinery. They are not considered cells as they have no plasma membrane or metabolism

Question 9

Prokaryotes regarding Chromosomes, Chromosome location, Histones, Nucleolus, Extrachromosomal DNA, Ribosomes and Cell Division?

Answer 9

Single circular, nuclear region, absent, absent, in plasmids, 70s and binary fission

Question 10

Eukaryotes regarding Chromosomes, Chromosome location, Histones, Nucleolus, Extrachromosomal DNA, Ribosomes and Cell Division?

Answer 10

Paired linear, membrane bound nucleus, present, present, in mitochondria and plasmids, 80s cytoplasmic/70s mitochondrial, mitosis or meiosis

Question 11

Structures present in Prokaryotes?

Answer 11

Cell wall (Internal membrane present in photosynthetic organisms only)

Question 12

Structures present in Eukaryotes?

Answer 12

Mitotic spindle, sterols in plasma membrane, internal membrane, ER, mitochondria, lysosomes, Golgi, peroxisomes and cytoskeleton

Question 13

What are the two electron microscopes?

Answer 13

TEM and SEM

Question 14

The 3 reasons to why the maximum size of a cell is limited?

Answer 14

1) After 50um, diffusion efficiency reduced
2) SA:V ratio as greater size means volume increasing more than SA
3) Distance from nucleus to the periphery

Question 15

The 3 ways cells can overcome limitations of cell diffusion?

Answer 15

1) Thin processes for direct transport
2) Giant multinucleate cells
3) Gap junctions

Question 16

Why are membranes important?

Answer 16

Membranes allow specialised environments to exist with different functions and different conditions

Question 17

What does the cytoskeleton contribute to?

Answer 17

Mechanical strength, Shape control and to Guide movement

Question 18

The Nucleus

Answer 18

Largest organelle
Visible with a light microscope
Contains packed genetic material
Contains DNA in chromosomes

Question 19

The Smooth ER

Answer 19

Biosynthesises membrane lipids and sterols

Involved in n-linked glycosylation and detoxification of Xenobiotics

Question 20

The Rough ER

Answer 20

Coated in ribosomes
Allows proteins for insertion and secretion to cell membrane
Proteins folded forming Cys-Cys bridges
Vesicles bud to the golgi

Question 21

The Golgi

Answer 21

Consist of 4-8 close stacked cisterna
Modifies proteins
Synthesises materials
Can direct new proteins in vesicles
Creates lysosomes

Question 22

The Peroxisome

Answer 22

Not very electron dense
involved in detoxification
enzymes which generate and degrade H2O2

Question 23

The Lysosomes

Answer 23

Electron dense spheres
Contain hydrolytic enzymes
Require low pH
Involved in organelle turnover

Question 24

The Mitochondria

Answer 24

Two layers
Inner membrane forms cristae to increase surface area
Contains DNA
Generates ATP via the krebs cycle