Topic 3: Voice of the genome.

Question 1

Describe a Nucleus.

Answer 1

Double membrane.
Contains DNA wrapped around Histone proteins in a complex called a chromatin.
Has a nucleolus where ribosomes are produced.

Question 2

Describe the Rough Endoplasmic Reticulum.

Answer 2

Flattened sacs enclosed by a membrane.
Folds and processes proteins made in the ribosomes on the organelles surface.

Question 3

Describe the Smooth Endoplasmic Reticulum.

Answer 3

Membrane bound sacs.
Produces and processes Lipids.

Question 4

Describe the Golgi Apparatus.

Answer 4

Curved sacs with vesicles surrounding the edges.
Modifies and packages proteins.

Question 5

Describe the Mitocondria.

Answer 5

Double membrane.
Inner membrane is called the cristae inside that is the matrix containing enzymes for respiration.

Question 6

Describe Centrioles.

Answer 6

Hollow cylinders.
Used in cell division.

Question 7

Describe Protein trafficking.

Answer 7

Proteins produced in Ribosomes on RER are folded in it.
Then transported to Golgi in vesicles.
At Golgi are modified.
Golgi packages proteins to be transported around cell or outside cell.

Question 8

Organelles of Prokaryotic cells.

Answer 8

Cell wall.
Slime capsule.
Plasmid.
Flagellum.
Pili.
70s ribosomes.
Mesosomes.

Question 9

Describe a Cell wall.

Answer 9

Rigid outer cover provides cell with strength and support.

Question 10

Describe Slime capsule.

Answer 10

Slimy layer helps retain moisture and adhere to surface.
Only in Prokaryotic cells.

Question 11

Describe a Plasmid.

Answer 11

Circular piece of DNA in Prokaryotic cells.

Question 12

Describe a Flagellum.

Answer 12

A tail like structure which rotates to move the cell.

Question 13

Describe a Pili.

Answer 13

Hair like structures which attach to other bacteria cells.
Allows exchange of plasmids.

Question 14

Describe Mesosomes.

Answer 14

Infolding of inner membrane.
Use is debated by scientists.

Question 15

Describe the Zona pellucida.

Answer 15

Protective coating which sperm has to penetrate in order for fertilisation to occur.
Hardens after sperm enters to stop polyspermy.

Question 16

Describe Cortical granules.

Answer 16

Releases substances which causes Zona pellucida to harden.

Question 17

Describe the structure of a sperm cell.

Answer 17

Head has acrosomes which are digestive enzymes that breakdown the zona pellucida.
Neck contains many mitochondria to produce energy for flagellum to move.

Question 18

Describe the stages of fertilisation.

Answer 18

Sperm cells gets to egg and releases acrosomes to break down Zona pellucida.
Sperm head fuses with cell membrane of egg allowing sperm nucleus to enter the egg cell.
Cortical reaction causes zona pellucida to harden.
Nuclei fuse forming full set of chromasomes.

Question 19

Name the three stages of cell cycle.

Answer 19

Mitosis.
Cytokinesis.
Interphase.

Question 20

Describe Mitosis.

Answer 20

Consists of prophase, metaphase, anaphase and telophase.

Question 21

Describe Cytokinesis.

Answer 21

Cytoplasm divides producing two daughter cells.

Question 22

Describe Interphase.

Answer 22

Three stages of Interphase:
G1- cell grows and DNA replicates.
S-Chromosomes replicate begin condensing into chromatin.
G2- Organelles replicate so each cell has a complete set.

Question 23

Describe Crossing over in Meiosis.

Answer 23

The exchange of sections of DNA between Homologous chromasomes.

Question 24

Describe Independent assortment.

Answer 24

There are various combinations of ways maternal and paternal chromosomes can be distributed between two daughter cells.

Question 25

Describe Stem cells.

Answer 25

Undifferentiated cells capable of dividing and giving rise to other cell types.

Question 26

Name the three types of stem cells.

Answer 26

Multipotent.
Pluripotent.
Totipotent.

Question 27

Describe a Multipotent stem cell.

Answer 27

Cell that can give rise to many different types of cell.

Question 28

Describe Pluripotent stem cells.

Answer 28

Cells that can give rise to many types of specialised cells but not placental cells.

Question 29

Describe Totipotent stem cells.

Answer 29

Can give rise to all types of specialised cells, including placental cells.

Question 30

Describe the process of Differential gene expression

Answer 30

A stimulus acts on unspecialised cells.
Activator or repressor molecules bind to promoter region.
Active genes are transcribed and translated.
Proteins change the structure and function of cells.

Question 31

Describe Monogenic.

Answer 31

Characteristics determined by one gene.
Often discontinuous variation.

Question 32

Describe Polygenic.

Answer 32

Characteristics determined by multiple genes.
Often continuous variation.

Question 33

Describe DNA methylation.

Answer 33

Process that adds a methyl group to DNA causes DNA to wrap tighter to histone stopping it being transcribed.

Question 34

Describe Acetylation.

Answer 34

Addition of a acetyl group causes activation of chromatin.

Question 35

Describe the Lac Operon

Answer 35

A gene in Bacteria which is suppressed by repressors unless in the presence of lactose.
Saves energy as the gene is for an enzyme breaking down lactose.