Inheritance Flashcards
What is a chromosome?
Thread-like structure found in nucleus and made of DNA
What’s DNA?
Double-helix molecule
What’s a gene?
A section of DNA that codes (contains information for making a protein)
What are somatic chromosomes?
Chromosomes that aren’t sex chromosomes
What is a protein?
A chain of amino acids
What are sex chromosomes?
Chromosomes that determine gender
What are homologous chromosomes?
Chromosomes that carry the same genes and form a pair
What is the result of mitosis?
Two genetically identical cells
What is the purpose of mitosis?
Growth and repair
What is meiosis?
A special type of cell division by which gametes (sex cells) are made
What does diploid mean?
2 sets of chromosomes
What does haploid mean?
1 set of chromosomes
What is the result of meiosis?
Four genetically different haploid cells (with only 23 chromosomes)
Where does meiosis take place?
In testes and ovaries
How many cells are produced in mitosis and meiosis?
- Mitosis - 2
* Meiosis - 4
What is variation?
Small differences between members of the same species
What is genetic variation?
Differences caused by genes inherited from parents
What is environmental variation?
Differences caused by the environment
What is an allele?
A version of a gene
What is a dominant allele?
Only 1 copy is necessary for characteristic to be shown
What is a recessive allele?
2 recessive alleles are needed (no dominant allele present) for characteristics to be shown
What is the genotype?
The genetic makeup, i.e. which alleles are present
What does homozygous mean?
Having 2 identical alleles
What does heterozygous mean?
Having 2 different alleles
What is the phenotype?
The characteristic that is shown
What does co-dominance mean?
Both alleles contribute to the phenotype, so that both characteristics are present at the same time
What is a carrier?
When someone has one recessive allele but doesn’t show the phenotype
What are mutations?
Changes in the DNA
What is a mutagen?
An agent that causes mutations
What are genetic diseases?
A condition or illness caused by mutations in genes or chromosomes
What holds the chromatids together?
Centromere
How is genetically engineered insulin is produced?
- Human cells contain a gene for making insulin.
- DNA is extracted from human cells.
- The insulin gene is cut out from DNA using a restriction enzyme.
- Bacteria cells contain short circular pieces of DNA called plasmids.
- The plasmid is extracted and cut using the same restriction enzyme.
- The enzyme DNA ligase is used to join the ends of the insulin gene and the plasmid create recombinant DNA.
- The plasmid holding the insulin gene functions as a vector and is used to transfer the insulin gene into bacteria.
- The transgenic bacteria reproduce and start making insulin protein.
- The insulin protein can be isolated and purified.
What is a plasmid?
A short circular piece of DNA found in bacterial cells
What is a restriction enzyme?
Enzyme that cuts DNA molecules at specific points
What is DNA ligase?
Enzyme that joints cut ends of DNA molecules
What is recombinant DNA?
DNA that has been created from different sources
What is a vector?
The means of transferring DNA into an organism (e.g. a plasmid or a virus)
What is a transgenic organism
An organism whose DNA has been genetically altered
What are totipotent stem cells?
- Can form any cell type.
* From day 1 - day 5 of a zygote
What are pluripotent stem cells?
- Can develop into most cells types
* From 1 week
What are multipotent stem cells?
- Can develop into some cell types
* From foetus to adult
Cuttings
- Remove a small part (stem or leaf) of the parent plant.
* Plant cutting into soul; it will then grow into a new plant.
Micropropogation
- Take a few cells/very small parts from the plant (=explants).
- Put them into culture medium (with nutrients and growth hormones).
- Grow into a callus and from that into a new plant.
Why does plant cloning work?
- Plants contain many meristem cells, which continuously divide by mitosis.
- Meristem cells are. Totipotent and can differentiate into all kinds of other plant tissues.
What are the advantages of reproducing transgenic (genetically modified) sheep by cloning?
- Ensures that all sheep are genetically identical.
- Ensures all sheep have the gene for the characteristic (e.g. producing clotting agent).
- More clotting agent is produced.
- More sheep are produced.
- Genetic modification of the animals does not have to be repeated.
