Biology Flashcards
Chromosomes
Thread-like structures found in the nucleus of cells that are made of DNA and protein.
What happens at the start of mitosis? ie. Interphase
Chromosomes replicate and become double-stranded.
What happens in the second stage of mitosis? ie. Prophase
Double-stranded chromosomes become visible.
What happens in the third stage of mitosis? ie. Metaphase
Double-stranded chromosomes line up along the equator of the cell.
What happens in the fourth stage of mitosis? ie. Anaphase
Chromosomes move to opposite ends of the cell.
What happens in the fifth stage of mitosis? ie. Telophase
Two nuclei form, each with a diploid number of chromosomes.
What happens in the end of mitosis?
Membranes form separating the two nuclei into two daughter cells.
What is the human genome project?
It was an international project that aimed to identify all genes 20 000- 25000 genes in the human genome, and determine the sequence of the 3 billion base pairs that make up human chromosomes.
What is the process of gene testing?
Scientists are able to test for a gene once its function in is known. This could help you avoid diseases that are controlled by lifestyle as well as genetics, such as the risk of heart disease or type-2 diabetes.
What does gene therapy do?
It has the potential to cure genetic diseases. In gene therapy, the defective gene is replaced with a normal gene.
What is a fossil?
The preserved evidence in rocks or soils of organisms that once existed on Earth.
Why is replication important?
The cell cycle is necessary for replacing dead or damaged cells. It is especially important in tissues such as skin and hair.
What is the fossil record?
A list showing all the species of living organisms that have been found as fossils as well as their location and age.
What is DNA?
The molecule that determines the genetic characteristics of most living things.
What is a Mendelian trait?
Where one gene accounts for one trait.
What are the 5 evidences of evolution?
- fossil record
- distribution
- comparative anatomy
- DNA and protein
- comparative embryology
What is needed for speciation?
- Variation
- Isolation
- Selection
What are the 4 types of fossils?
- original fossils - bones
- replacement fossils - chemically changed into another mineral
- carbon film fossils - dead body partially decays and leaves behind a layer of carbon
- indirect fossils - preserved remains of things, eg footprints
What are the 5 types of preserving the environment?
- Permafrost - frozen indefinitely
- Amber - encasing something in solid plant sap or gum
- tar - occurs where oil seeps naturally out of the ground and onto the surface.
- peat - partly decomposed remains of plants ie. Moss
- dry air - bacteria and fungi can’t survive in dry conditions - they thrive in moisture
What does mitosis produce?
It produces 2 daughter cells that are identical to the parent cell
- involved in the growth and repair of the body
What does meiosis produce?
It produces gametes (egg and sperm cells) that have half the number of chromosomes of the parent.
What is an analogous structure?
- They have a similar structure and same function but they aren’t from the same species.
- structures that appear similar or have the same function but are controlled by different genes.
What is a homologous structure?
- They have the same feature with the same structure but they have a different function.
- structures that are controlled by some of the same inherited genes.
What is artificial selection?
The process by which people choose to breed particular organisms with desirable features.
What is gene testing?
- testing genes for diseases - allows couples to decide to have children or not
What is gene therapy?
When a elective/unwanted gene is replaced with a normal gene
How is the fossil record incomplete?
- not every animal can produce a fossil
- most fossils come from marine animals with hard body parts
Eg. Jellyfish cannot make fossils
How are fossils evidence of evolution?
- show what organism were like millions of years ago
- compare to descendants of these organisms
What is a species?
A group of living organisms consisting of similar individuals, capable of exchanging genes and creating offspring.
