DNA, Genes etc Flashcards
What is a gene ?
A section of DNA which codes for a protein or characteristic
How do cells make proteins?
By stringing amino acids together in a particular order
What do genes tell us?
What order to put the amino acids together
What can DNA determine?
What proteins the cell produces, e.g. Haemoglobin, which in turn determines what type of cell it is, e.g. Red blood cell
What is DNA fingerprinting?
A way of cutting up a persons DNA into small sections and then separating them
What can DNA fingerprinting be used in?
- Forensic science - DNA can be taken from a crime scene and is compared with a sample from a suspect
- Paternity testing- to see if a man is father to a child
What are the arguments for and against DNA fingerprinting?
For:
-a national genetic database would make it easier to check DNA from a crime scene against everyone in the country to find the criminal quicker
Against:
-it is an invasion of privacy
-people worry the data may not be safe and may be used for other things
-scientific problems, false positives can occur if errors are made in the procedure or if the data is misinterpreted
What is meant by mitosis?
When a cell reproduces itself by splitting to form two identical offspring
What does mitosis do?
It makes new cells for growth and repair
What is a chromosome ?
Large molecules of as DNA In a double helix structure
What is variation?
Differences between individuals of a species
What are stem cells?
Undifferentiated cells - they develop into different types of cell depending on what instructions they’re given
What are alleles?
Different versions of a gene
How does DNA fingerprinting work?
- DNA is extracted
- enzymes are used to split up the DNA
- gets put into gel with electromagnetic waves
Describe mitosis
The DNA is duplicated
The DNA is now copied and forms X shaped chromosomes
The chromosomes line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell
Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells
The cytoplasm divides and two new cells containing the exact same DNA are produced (which are identical )
What is meant by meiosis ?
Meiosis produces cells which have half the normal number of chromosomes
Why are some people against stem cell research?
- human embryos shouldn’t be used for experiments since it is a potential human life
- doctors should concentrate more on finding and developing other sources of stem cells so people could be helped without having to use embryos
Why are some people for Stem cell research?
- embryos used are often unwanted ones that would just have been destroyed. It is better to put them to use
- it has the potential to save lives and improve science
What chromosomes do men have?
X and Y chromosome
The Y chromosome is what causes male characteristics
What chromosomes do women have?
Two X chromosomes
The XX combination allows female characteristics to develop
What does recessive mean?
The characteristic that will show up in the offspring only if both of the alleles are inherited
What is a dominant allele?
The characteristic that will show up in the offspring even if only one of the alleles were inherited
What is a genotype?
The pair of alleles that has been inherited
What are hereditary units?
Genes
What is a phenotype?
The physical expression of a gene
What is cystic fibrosis caused by?
A recessive allele
To have cystic fibrosis, what must you have?
Both copies of the allele
What is polydactyly caused by?
A dominant allele
When can polydactyly be inherited?
If just one parent carries the defective allele
What is embryo screening?
Where a single cell is removed from an embryo for 2-3 days after it has been conceived and is tested for genetic abnormalities
What are the arguments against embryo screening?
- there may be a point where people want to screen their embryos to pick the most ‘desirable’ one
- the reject embryos are destroyed
- implies that people with genetic problems are ‘undesirable ‘
- screening is expensive
What are the arguments for embryo screening?
- it will help stop people suffering
- there are laws on it. Parents cannot choose the embryo they want
- during IVF, most of the embryos are destroyed anyways, screening allows the selected one to be healthy
- treating disorders can cost a lot of money
Describe meiosis
DNA is copied , chromosomes make identical copies of themselves
Similar chromosomes pair up
Sections of DNA get swapped
Cell divides, pairs of chromosomes divide
Four gametes produced with only a single set of chromosomes in it
