Chapter #16 - Chromosomes, Genes and Proteins Flashcards
Chromosomes
A length of DNA found in the nucleus. It contains genetic info in the form og different genes
Under what circumstances can chromosomes be observed?
They can be seen with a regular light microscope only when cells are dividing
What are chromososmes made of?
DNA in a double helix which is made up of genes
How do chromososmes vary within your body?
(depending on what part of the body they are in)
Every cell in the body has all of it’s DNA. However, the cells are specialized to “read” only the parts that are rfelevent to that part of the body
Draw a labled diagram of a chromosome
DNA
A molecule that contains genetic info in the form of genes.
What does DNA carry?
Each molecule of DNA carries a code whch the cell which proteins to make. So, each chromosome carries instructions for making diff proteins.
Gene
A length of DNA molecule that coede for one protein.
What do genes determine?
Many of our features such as:
* eye color
* hair color
* nose shape
* genetic diseases
Alleles
Alternative forms of the same gene.
Moste genes come in more than one form.
Homologous pair
A pair of chromosomes which are similar. In each pair, one is from the mother and the other from the father.
Heterozygous
Having 2 different alleles of a particular gene (e.g. Gg).
Homozygous
Having 2 identical alleles of a particular gene (e.g. GG or gg)
How many chromosomes do humans have?
Humans have 46 chromosomes in each of our cells. (23 homologous chromosomes)
Do all humans have the same types of alleles?
Humans have many genes in common but we differ in alleles. No 2 humans have the exact same combination of alleles (except for identical twins)
The 46 chromosomes in a human body cell nucleus are difficult to distinguish when packed inside the nucleus. How are the similar pairs in the 46 chromosomes identified by scientists?
So, scientists seperate them and arrange them according to size and appearence.
What chromosome pair does not match?
The sex chromosome. In males, the y chromosomes is smaller than the x chromosome.
How are chromosomes organized and identified by scientists?
- Put into homologous pairs
- Order from largest to smallest
- They are numbered this way
What are homologous pairs made up of?
One chromosome is inherited by the mother and the other from the father.
Mitosis
The division of a cell nucleus resulting in 2 genetically identicle nuclei.
When is mitosis used by animal or plant cells?
To repair or grow (also in aesexual reproduction)
Replication
Before mitpsis begins, exact copies of all chromosomes are made.
What steps occure during mitosis?
- Each chromosome spilts (after replication)
- 2 daughter cells that are genetically identicle yo eachother are produced
- They are also genetically identicle to parent cell
Meiosis
The division of a diploid nucleus resulting in 4 genetically different haploid nuclei.