Unit 1 cells

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Sophia

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What are somatic cells?
Any cell in the body other than cells involved in reproduction.
What are germline cells? 
Gametes that divide to form more gametes.
What do somatic cells divide by?
Mitosis to produce more somatic cells.
What do germline cells divide by?
Mitosis and Meiosis.
What are the steps of mitosis?
The DNA replicates to form 2 copies of each chromosome.
The membrane breaks down and the chromosomes line up across the center of the cell.
One set of chromosomes is pulled to each end of the cell and the nucleus divides.
The cytoplasm and cell membranes divide to form 2 identical cells.
What are the steps of meiosis?
Chromosomes make identical copies of themselves.
Similar chromosomes pair up.
Chromosomes divide to form 2 diploid cells.
The cells divide again to form 4 haploid cells.
What does the term diploid mean? 
A full set of chromosomes (46 in total - 2 pairs of 23).
What does the term haploid mean? 
Half a set of chromosomes (1 set of 23).
What are the two types of stem cells?
Embryonic stem cells, tissue stem cells.
What does the term pluripotent mean? 
The embryonic stem cells can give rise to all cell types.
What does the term multipotent mean?
Tissue stem cells can only give rise to limited types of cells.
Where are embryonic stem cells found?
In early stage embryos.
Where are tissue stem cells found?
A mature organism.
What are 3 examples of therapeutic use of stem cells?
Bone marrow transplants, skin grafts, corneal transplants.
How can stem cells be used as model cells?
To study how diseases develop or for drug testing.
What are 2 ethical concerns with using embryonic stem cells?
Is it right to create embryos for therapy and destroy them in the process.
At what stage should an embryo be regarded and treated as a person.
What are 3 clinical concerns with using embryonic stem cells?
Embryonic stem cells are hard to retrieve and store.
No guarantee that the treatment will be successful.
The stem cells can have mutations and can potentially become cancerous cells.
What is cancer?
Cells divide uncontrollably by mitosis and do not respond to regulatory signals.
What is a tumour?
A clump of abnormal cells.
What does the term benign tumour mean?
Grows slowly within a membrane. Can be easy to treat and does not spread to other parts of the body.
What does the term malignant tumour mean?
Grows quickly and invades other parts of the body.
Cells may fail to attach to each other, then travel via bloodstream to form secondary tumours in other parts of the body. This is called metastasis.
What are 3 examples of lifestyle factors that increases the likelihood of developing cancer?
Chemical carcinogens in cigarette smoke, increasing the chances of lung cancer.
Excessive alcohol intake is linked with certain cancers such as liver cancer.
Diet, including fat and salt intake can increase the chances of developing cancer such as bowel and uterine cancer.
What are 2 examples of industrial and environmental factors that increase the likelihood of developing cancer?
Exposure to ionising radiation increases the chances of skin cancer.
Exposure to chemical carcinogens such as smoke can increase the chances of developing lung cancer.
What are nucleotides made up of?
5 carbon sugars, phosphate group, and a base.
What is the complementary base pairing rule in DNA?
Adenine binds to Thymine.
Cytosine binds to Guanine.
What is the complementary base pairing rule in RNA?
Adenine binds to Uracil.
Cytosine binds to Guanine.
What is the difference between the structure of DNA and RNA?
DNA is double stranded, RNA is single stranded.
DNA bases include Thymine, RNA bases don't include Thymine and contains Uracil instead.
What is the 5' end of DNA?
Phosphate end.
What is the 3' end of DNA?
Deoxyribose sugar end.
What does antiparallel mean?
The two strands of DNA run in opposite directions.
What is a primer?
A short strand of nucleotides that binds to the 3' end of the template DNA strand to allow DNA polymerase to add free DNA nucleotides.
What are the stages of DNA replication?
DNA helix strands unzip and unwound.
Hydrogen bonds weaken between bases.
DNA polymerase adds free nucleotides to the template strands.
Leading strand is synthesised continuously.
Lagging strand is synthesised in fragments.
Ligase seals the synthesised fragments together.
Strands twist to form the double helix.
What is polymerase chain reaction (PCR)? 
Amplifies DNA in vitro.
Give 3 reasons why pcr would be used.
To diagnose genetic disorders.
To solve paternity lawsuits.
To identify a criminal.
What are the stages of pcr?
DNA is heated up to between 92 and 98 degrees C to denature and seperate the two strands.
DNA is cooled down to between 50 and 60 degrees C allow primers to attach to target DNA region.
DNA is heated up to between 70 and 80 degrees C, heat tolerant polymerase is added to replicate the DNA. 2 new strands are formed.
The cycle repeats over and over again.
What is gene expression?
When genes are turned on to produce a required protein or carry out a specialised function.
What is protein synthesis?
The DNA code remains in the nucleus.
mRNA carries a copy of the DNA from the nucleus to the ribosome where protein synthesis takes place.
The protein produced depends on the template used. If the sequence changes a different protein will be made.
Carrier molecules (tRNA) brings specific amino acids to add to the sequence in the correct order.
What is the characteristics and role of mRNA?
Messenger RNA carries a copy of the gene to be expressed from the nucleus to the ribosome.
Every three bases codes for a protein (codon).
Linear molecule.
What is the characteristics and role of tRNA?
Transfer RNA is made from a single strand of RNA which folds due to base pairing to form the unusual shape.
Has a triplet anti-codon site and an attachment site for a specific amino acid.
Cloverleaf shaped molecule.
What is the characteristics and role of rRNA?
Ribosomal RNA forms the ribosome where protein synthesis takes place.