Biology (Combined) Flashcards
What are the three stages of the Cell Cycle (the life of a cell).
- Interphase: Makes up most of the life of a cell. During interphase, cells grow and carry out their life functions. In cells that will divide, the nucleus makes a copy of its DNA in a process called replication.
- Mitosis: During this stage, the nucleus of the cell divides into two equal and identical parts. Each part has a copy of the DNA.
- Cytokinesis: During this stage, the two equal, identical parts of the cell separate. The results of this stage is two identical cells, each with a nucleus and DNA.
What are the four phases of mitosis?
- Prophase: The duplicated chromosomes form into an X shape and the nucleus disappears. Spindle fibres, which are tiny tube-like sructures made of protein, begin to form in plant and animal cells.
- Metaphase: The duplicated chromosomes line up across the middle of the cell.
- Anaphase: The duplicated chromosomes move apart to opposite ends of the cell.
- Telophase: A nucleus forms around the chromosomes at the opposite ends of the dividing cell.
What is a gene mutation?
A gene mutation is a change in the genetic material (DNA) of a gene. Changes to DNA may cause proteins to be made incorrectly or with an incorrect shape.
What can cause gene mutations?
Gene mutations can happen randomly without a specific cause.
But there are also factors called mutagens that can cause mutations, including:
- Radiation, such as X rays and UV rays
- Cigarette smoke and other poisonous chemicals such as pesticides
Are mutations good or bad?
They can be both – or neither good or bad.
Negative mutations are harmful to an organism. For example, a mutation that makes blood cells have a curved shape which prevents the cells from carrying oxygen well.
Positive mutations help an organism. For example, a mutation that prevents someone from getting infected by HIV.
Most mutations have no impact on an orgamism. They are called neutral mutations. For example, Spirit Bears are black bears that have a mutation that turns their fur white.
Can mutations be fixed?
Some mutations can be treated with drugs or surgery. New techniques for treating gene mutations are called “gene therapy”.
What is asexual reproduction?
Asexual reproduction is the formation of a new individual that has the same genetic information as its parent. The individual is a clone, or exact copy, of its parent.
What types of organisms does asexual reproduction occur in?
Asexual reproduction occurs in one-celled organisms such as bacteria and multicellular organisms such as plants.
What are the five types of asexual reproduction? (Just list them)
- Binary fission
- Budding
- Fragmentation
- Spore formation
- Vegetative reproduction
What are the advantages of asexual reproduction?
- Only one parent is required, so there is no need to find a mate.
- Large colonies can out-compete other organisms for nutrients and water.
- Large numbers of offspring reproduce very quickly.
- Species can survive if the number of predators increases.
- Offspring can reproduce shortly after they are formed.
- Offspring are genetically identical to their parent and so can survive in the same environment as their parent.
What are the disadvantages of asexual reproduction?
- Offspring compete for food and space.
- Extreme changes can wipe out entire colonies because all of the offspring are genetically identical.
- Negative mutations can destroy many offspring.
Why do human sometimes help other organisms reproduce asexually? And what are some examples of it.
Humans may want to preserve the DNA of an organism or make large numbers of a particular type of organism with a useful trait. Two examples:
- Growing new plants from the cut ends of plant stems and roots.
- Making clones of animals by taking the nucleus from one type of cell and putting it into an egg cell that has had its nucleus removed.
What are stem cells and how are they being used in medicine?
Stem cells are cells that can divide to form one of many different types of cells. Stem cells that come from human embryos can become any of the 200 types of cells in the human body. Stem cells that come from specific body tissue can become only a few types of body cells. Doctors are working to use stem cells to treat certain disorders such as diabetes and cancer.
What is binary fission?
Binary fission is a form of asexual reproduction.
The splitting of a single parent cell into two equal parts that have the same copies of genetic material. (Examples: some kinds of bacteria, amoeba.)
What is budding?
Budding is a form of asexual reproduction.
A group of rapidly dividing cells develops on an organism and breaks away to become a new organism. (Examples: Some simple multicellular organisms such as hydras and sponges. One-celled yeast.)
What are gametes and how are they used in sexual reproduction?
Gametes, also known as sex cells, are required during sexual reproduction.
The male gamete is the sperm. The female gamete is the egg.
The sperm combines with the egg to form a zygote in a process called fertilization. Half of the genetic material of the zygote comes from the sperm and other half from the egg.
What are haploid and diploid?
Haploid: Gametes that have half the normal number of chromosomes.
Diploid: When the two gametes combine they form a cell having a full set of chormosomes.
These chromosomes are paired and are called homologous chromosomes. In the pair, one chromosome comes from the female parent and the other comes from the male parent.
What is meiosis?
During meiosis, a diploid cell undergoes two consecutive cell divisions to produce four haploid cells. These four cells are the gametes that will be involved in sexual reproduction.
Once the cell has divided once, the two daughter cells each divide again.
What part of the plant does pollen come from and where does it land?
Pollen grains come from the male anther of a flower and are deposited on the female stigma of a flower.
In most plants, pollen from another plant is used.
