Topic 3- Voice of a Genome Flashcards
Describe the structure and function of a nucleus
enclosed by membrane containing poere
contains chromosomes
contains nucleolus where ribosomes are made
Dna replication and transcription takes place
controls the cell
Describe the structure and function of a nucleolus
produced ribosomes
Describe the structure and function of a ribosome
-enzyme that assists in RNA translation for protein synthesis
Describe the structure and function of rough endoplasmic reticulum
system of iner connected flattened sacs with ribosomes attached to out surface, for lipid protein (due to ribosomes present) and steroids
Describe the structure and function of smooth endoplasmic reticulum
like rough but no ribosome
synthesis lipids and steroids
Describe the structure and function of mitochondria
contains folded inner membrane called cristae
site of aerobic respiration
Describe the structure and function of centrioles
Hollow tubes of a ring of 9 protien microtubes
involved in spindle formation in nuclear division
Describe the structure and function of lysosomes
sacs containing digestive enzymes
involved in breakdown of unwanted structures in the cell
Describe the structure and function of Golgi apparatus/body
membrane bound vesicles that modifie protien and packages it for transport
Describe the process of protein manufacture and transport
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
Define the term stem cell
a cell that can divide via mitosis to form more stem cells and differentiate into different cell types
Define the term pluripotency
the inner mass cells of a blastocyst that can differentiate into any cell except extra-embryonic cells
Define the term multipotency
stem cells that can only differentiate into a few types of cells
Define the term totipotency
stem cell that can differentiate into any type of cell including extra embryonic cells
Explain how pluripotent cells are extracted from an embryo
Cells are extracted from the inner mass of a blastocyst with a needle, the embryo is destroyed.
Give the ethical arguments for and against the use of embryonic stem cells in research/medicine
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
State what an induced pluripotent stem cell (IPSC) is
A pluripotent stem cell tgat has been created from an adult stem cell through genetic reprogramming
Explain why IPSCs are advantageous over embryonic stem cells
- uses own cells, no rejection (for people who havent kept any cells from birth)
- no embryo is destroyed so less ethical issue
Describe the role of histone modification in epigenetics
‘tails’ of histones are modified
makes DNA less compact and more accessible for transcription
Turns genes ON
Describe the role of methyl groups in epigenetics
makes DNA more tightly wound
less accessible for transcription
turns genes OFF
Explain why genetically identical twins look less similar to each other as they age
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
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)
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
what happends in G1 and G2?
gap phase 1+2
cell keeps growing protiens and new organelles for cell division
what is s phase in the cell cycle?
DNA replication
What happens in the interphase of the cell cycle?
cell carries out normal functions but prepares to divide (G1, S, G2)
replication of DNA and organelles
ATP content increased
what happens in the Prophase of Mitosis?
Chromosomes condense
Centrioles start moving to opposite sides of the cell forming spindles
the nuclear envelope breaks down leaving chromosomes free in the cytoplasm
what happens in the metaphase of mitosis?
chromosomes line up along the middle of the cell and attach to spindles by their centromere
What happens in the anaphase of mitosis?
the centromeres divide
seperating sister chromatids
spindles contract pulling chromatids to opposite ends of the cell
What happens during the Telophase of Mitosis?
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.
what are the 4 stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
(pee mat ahhh toot!)
what are the steps of a cortical reaction?
cortical granules fuse with egg cell membrane
enzyme releases into zona pellucida
zona pellucida thickens and harderns
what are the steps of fertilisation?
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
what happens in the acrosome reaction?
acrosome in head of sperm fuses with egg membrane and releases digestive enzymes via exocytosis
What are the products of meiosis?
- 4 gametes that are non genetically identical
chromosomes are rearranged with a new combination of genes
what is the importance of meiosis?
creates genetic variation
describe how a stem cell becomes specilised
-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
explain why males are more likey to suffer from X-linked disease than females
males only have one X chromosome
so only need one allele to show phenotypes (if it is a recessive phenotype)
