Topic 3- Voice of a Genome

Question 1

Describe the structure and function of a nucleus

Answer 1

enclosed by membrane containing poere
contains chromosomes
contains nucleolus where ribosomes are made

Dna replication and transcription takes place

controls the cell

Question 2

Describe the structure and function of a nucleolus

Answer 2

produced ribosomes

Question 3

Describe the structure and function of a ribosome

Answer 3

-enzyme that assists in RNA translation for protein synthesis

Question 4

Describe the structure and function of rough endoplasmic reticulum

Answer 4

system of iner connected flattened sacs with ribosomes attached to out surface, for lipid protein (due to ribosomes present) and steroids

Question 5

Describe the structure and function of smooth endoplasmic reticulum

Answer 5

like rough but no ribosome
synthesis lipids and steroids

Question 6

Describe the structure and function of mitochondria

Answer 6

contains folded inner membrane called cristae
site of aerobic respiration

Question 7

Describe the structure and function of centrioles

Answer 7

Hollow tubes of a ring of 9 protien microtubes
involved in spindle formation in nuclear division

Question 8

Describe the structure and function of lysosomes

Answer 8

sacs containing digestive enzymes
involved in breakdown of unwanted structures in the cell

Question 9

Describe the structure and function of Golgi apparatus/body

Answer 9

membrane bound vesicles that modifie protien and packages it for transport

Question 10

Describe the process of protein manufacture and transport

Answer 10

protein is translated on the ribosome
protien enters the RER and is folded to form the 3D shape
the folded protein is packaged in a vesicle
vesicle fuses with the Golgi
Golgi modifies protein for its function
modified protein is packaged into scretetory vesicle
vesicle fuses with cell membrane and releases protein via exocytosis

Question 11

Define the term stem cell

Answer 11

a cell that can divide via mitosis to form more stem cells and differentiate into different cell types

Question 12

Define the term pluripotency

Answer 12

the inner mass cells of a blastocyst that can differentiate into any cell except extra-embryonic cells

Question 13

Define the term multipotency

Answer 13

stem cells that can only differentiate into a few types of cells

Question 14

Define the term totipotency

Answer 14

stem cell that can differentiate into any type of cell including extra embryonic cells

Question 15

Explain how pluripotent cells are extracted from an embryo

Answer 15

Cells are extracted from the inner mass of a blastocyst with a needle, the embryo is destroyed.

Question 16

Give the ethical arguments for and against the use of embryonic stem cells in research/medicine

Answer 16

Against
- embryo considered living
-against some religions
-embryonic stem cells are unstable and can cause tumors

For
- less money and lab animals used testing new drugs
- no waiting list for organ transplant
- cells are identical so no risk of rejection

Question 17

State what an induced pluripotent stem cell (IPSC) is

Answer 17

A pluripotent stem cell tgat has been created from an adult stem cell through genetic reprogramming

Question 18

Explain why IPSCs are advantageous over embryonic stem cells

Answer 18

• uses own cells, no rejection (for people who havent kept any cells from birth)
• no embryo is destroyed so less ethical issue

Question 19

Describe the role of histone modification in epigenetics

Answer 19

‘tails’ of histones are modified

makes DNA less compact and more accessible for transcription

Turns genes ON

Question 20

Describe the role of methyl groups in epigenetics

Answer 20

makes DNA more tightly wound

less accessible for transcription

turns genes OFF

Question 21

Explain why genetically identical twins look less similar to each other as they age

Answer 21

Epigenics- differences are caused by the environment, changing the ways genes are expressed and therefor the twins appearance over time, making them look different to each other although they are genetically identical

Question 22

Explain how we know epigenetics can be passed from parent to offspring (hints: consider the case study of rats smelling cherries and experiencing an electric shock and/or fungicide given to pregnant rats and impact on sperm count)

Answer 22

certain genes will be turned on and off via DNA methylation or histone modification depending on the treatment of offspring by parent

for example the offspring of the bad mother rats, when given to the good mother rat had the same genes expressed due to no methylation, this meant that the offspring could process stress hormones better so were calm ‘good’ mothers themselves

Question 23

what happends in G1 and G2?

Answer 23

gap phase 1+2

cell keeps growing protiens and new organelles for cell division

Question 24

what is s phase in the cell cycle?

Answer 24

DNA replication

Question 25

What happens in the interphase of the cell cycle?

Answer 25

cell carries out normal functions but prepares to divide (G1, S, G2)

replication of DNA and organelles
ATP content increased

Question 26

what happens in the Prophase of Mitosis?

Answer 26

Chromosomes condense

Centrioles start moving to opposite sides of the cell forming spindles

the nuclear envelope breaks down leaving chromosomes free in the cytoplasm

Question 27

what happens in the metaphase of mitosis?

Answer 27

chromosomes line up along the middle of the cell and attach to spindles by their centromere

Question 28

What happens in the anaphase of mitosis?

Answer 28

the centromeres divide
seperating sister chromatids
spindles contract pulling chromatids to opposite ends of the cell

Question 29

What happens during the Telophase of Mitosis?

Answer 29

Chromatids reach opposite poles on the spindle
they uncoil and become long again called chromosomes

a nuclear envelope forms around each group of chromosomes, now 2 nuclei

cytoplasm divides and 2 genetically identical daughter cells are made.

Question 30

what are the 4 stages of mitosis?

Answer 30

Prophase
Metaphase
Anaphase
Telophase

(pee mat ahhh toot!)

Question 31

what are the steps of a cortical reaction?

Answer 31

cortical granules fuse with egg cell membrane

enzyme releases into zona pellucida

zona pellucida thickens and harderns

Question 32

what are the steps of fertilisation?

Answer 32

ovum secretes chemicals

acrosome reaction to break down zona pellucida

fusion of sperm and ovum haploid nucleus to make diploid nucleus

cortical reaction to prevent polyspermy

Question 33

what happens in the acrosome reaction?

Answer 33

acrosome in head of sperm fuses with egg membrane and releases digestive enzymes via exocytosis

Question 34

What are the products of meiosis?

Answer 34

• 4 gametes that are non genetically identical

chromosomes are rearranged with a new combination of genes

Question 35

what is the importance of meiosis?

Answer 35

creates genetic variation

Question 36

describe how a stem cell becomes specilised

Answer 36

-stimulus from surrounding cells
-activation of some genes
- only activated genes are transcribed
- mRNA is translated on ribosomes
- makes a protien which gives the cell its function
-cell is differentiated

Question 37

explain why males are more likey to suffer from X-linked disease than females

Answer 37

males only have one X chromosome

so only need one allele to show phenotypes (if it is a recessive phenotype)