Chapter 2.2 Flashcards
(13 cards)
Where is DNA Located?
DNA is located in the nucleus of a cell (control centre).
What is a Gene?
Genes are genetic instructions that code for a particular trait Eg. Shape of earlobes, eye colour
Genes are a segment of the DNA molecule with a coded set of instructions in its base sequence for a specific protein product
What are Chromosomes?
They are super tiny thread like structures inside the nucleus of a cell.
Chromosomes can only be seen when it is or is about to divide .
Chromosomes cannot be seen any other time because the coils are unwound and DNA is spread throughout the nucleus.
Chromo- colour Some- body
Called this cause scientists stain to see them.
What is DNA?
DNA is deoxyribose neuclic acid which is a chemical substance that has encoded genetic instructions of an organism and gives its inherited features and traits.
How does DNA, Genes and Chromosomes relate?
Genes are segments of DNA which are organised into larger structures called chromosomes which are found in the nucleus of a cell.
DNA- Genes- Chromosomes- (inside nucleus)
What is the difference between Gonads and Gametes?
Gonads are the sex cell producing organs Eg. testicles and ovaries
Gametes are the sex cells Eg sperm and ovum
What is the difference between somatic cells and sex cells?
Somatic cells are body cells Eg adipose tissue cells, RBC, muscle cells etc. They have chromosomes in pairs within the nucleus. (Except rbc which looses a nucleus to hold more oxygen.)
Sex cells are reproductive cells (sperm and egg (ovum)) And are also known as gametes, found in gonads.
What are the 2 types of chromosomes,and what is the difference between them?
Somatic cells contain 23 pairs of chromosomes ( one from each parent).
An autosome are non -sex chromosomes and define an individual’s characteristics and inherited traits. Autosome are paired from 1-22 (1=largest 22= smallest).
Sex Chromosomes - gender defining chromosomes ( X or Y) which are found in sex cells.
What is the difference between Homologous and non-Homologous?
Homologous describes members of each matching pair of chromosomes.
Non-Homologous describes chromosomes that do not match with the other pair.
Eg 21 chromosome - 21 chromosome = homologous
21 chromosome - 3 chromosome = non-Homologous
What is a Karyotype? What does it tell?
A Karyotype is the number and general appearance(size, shape , banding position) of a set of chromosomes in a somatic cell
Karyotyping - when cells are about to divide they are stained and placed on a slide to view and be photographed. The photographs are cut and rearranged to Homologous groupings. ( largest to smallest - 1 to 23)
Karyotyping is important as it can tell a variety of chromosomal disorders Eg Down syndrome and Turner syndrome …
the gender can also be determined.
What is the difference between trisomy and Monosomy?
Trisomy is where there is 3 copies of a chromosome instead of 2 Eg addition to a number 21 chromosome (3x21 chromosome instead of 2x21) -> this results in Down syndrome
Monosomy is a mutation which that results in only one sex Chromosome (X,0) which results in Turner syndrome.
What is telomerase and telomere?
Telomere is a cal of DNA in the top of the chromosome which enables DNA to be replicated safely without losing valuable information.
- each time a cell divides, these telomere shorten however. When the telomere shorten and drop below a certain length, the cells stop dividing and dies - part of ageing.
Telomerase is the enzyme involved in maintains and repairing telomeres.
Who is Elizabeth Blackburn?
Elizabeth Blackburn is a Tasmanian born scientist who was awarded a Nobel prize in philosophy and Medicine in 2009 for discovering how chromosomes are protected by telomere and the enzyme telomerase maintains it in 1970.
