Inheritance. Flashcards
How does DNA control cell functions?
DNA controls cell function by controlling the production of proteins (including enzymes, membrane carriers, and neurotransmitter receptors).
What does the sequence of bases in a gene determine?
A sequence of bases in a gene determines the sequence of amino acids used to make a specific protein.
What do different shapes of amino acids give?
Different shapes of amino acids give different shapes to protein molecules e.g. hemoglobin, amylase, and lipase.
Why are many genes in a particular cell not expressed?
Most body cells in an organism contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs e.g. genes for making heart muscle are also in the brain but are not switched on.
Describe the six steps of protein synthesis.
- The gene coding for the protein remains in the nucleus.
- Messenger RNA (mRNA) is a copy of a gene.
- The mRNA molecules are made in the nucleus and move to the cytoplasm.
- The mRNA passes through ribosomes.
- The ribosome assembles amino acids into protein molecules.
- The specific sequence of amino acids is determined by the sequence of bases in the mRNA.
What is a haploid nucleus?
A haploid nucleus is a nucleus containing a single set of chromosomes e.g. in gametes i.e. a sperm and an egg.
What is a diploid nucleus?
A diploid nucleus is a nucleus containing two sets of chromosomes e.g. in body cells. In a diploid cell, there is a pair of each type of chromosome.
In a human diploid cell, how many pairs are there?
In a human diploid cell, there are 23 pairs.
What is mitosis?
Mitosis is nuclear division giving rise to genetically identical cells.
What happens during cell division?
When cells divide, the old cell divides into two new daughter cells. The nucleus divides first then the cytoplasm.
What is the role of meiosis?
- Meiosis results in genetic variation.
- Meiosis is involved in the production of gametes for sexual production.
What are the four roles of mitosis?
- Growth all over animals and in plants in the cambium and in meristems at root and stem tips.
- Repair of damaged tissues e.g. wounds.
- Replacmenr of worn out cells e.g. red blood cells.
- Asexual reproduction: in plants, fungi and bacteria by binary fission.
What happens during mitosis?
The two daughter cells separate so that each new cell gets a copy of each chromosome and maintains the chromosome number.
What are stem cells?
Stem cells are unspecialized cells that divide by mitosis to produce daughter cells that can become specialized for specific functions e.g. muscle cells, skin cells, etc.
Where do adults have stem cells and what are they for?
Adults have stem cells in bone marrow to produce red blood cells and phagocytes, and under the outer layer of skin to produce new skin cells.
What happens as an embryo in regards to stem cells?
As the embryo develops, the cells begin to take on different roles. Once a cell has differentiated it cannot change its role.
What do medical researches hope to use stem cells for?
Medical researchers are hoping to use stem cells to cure diseases e.g. type 1 diabetes, by using stem cells to replace the pancreatic cells that produce insulin.
What is meiosis?
Meiosis is reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells.
What provides the raw material for selection, and allows organisms to evolve in response to changing environments?
Gametes are genetically different from the parent cell. Fertilization is random and there are many possible combinations of genes so the fertilized diploid cells (zygote) produced are not genetically identical. This provides the raw material for selection and allows organisms to evolve in response to changing environments.
Describe the process of meiosis.
One pair of homologous chromosomes line up and are copied and then there are two divisions of the cell resulting in 4 gametes.
