chapter 7a genes and chromosomes

Question 1

What do nucleotides consist of

Answer 1

A phosphate group
Deoxyribose sugar
Nitrogen containing base: adenine (A), thymine (T), cytosine (C) or guanine (G)

Question 2

whats a gene

Answer 2

A gene is a particular section of DNA that codes for the creation of an individual polypeptide chain
Each person has 2 copies of each gene, one inherited from their mother and the other from their father
There are roughly 25,000 different genes inside each of your cells

Question 3

whats a genome

Answer 3

The collection of genes in a cell is known as the genome, which houses all the genetic information needed to build and maintain you.
An organisms genome is the sum total of all its DNA

Question 4

what are alleles

Answer 4

different forms of the same gene but with small differences in their base sequence

Question 5

whats a chromosome

Answer 5

Each molecule of DNA is coiled tightly around histone proteins and packaged into thread like structures called chromosomes
Human somatic cells mostly contain 46 chromosomes and therefore have a diploid number of 2n = 46

Question 6

6 parts of the chromosome

Answer 6

telomeres
DNA molecule
Centromere
sister chromatids
short arm
long arm

Question 7

what are homologous chromosomes

Answer 7

Each set of 23 chromosomes within an human nucleus are a pair of homologous chromosomes
Criteria for homologous chromosomes:
They are the same in size and length
They have the same centromere position
They share the same genes at the same gene loci

Question 8

what is Aneuploidy and what are the three types of it

Answer 8

abnormality where there is an incorrect number of total chromosomes caused by the addition or loss of an individual chromosome. In humans this means having more or less than 46 chromosomes

Monosomy – one missing chromosome (2n – 1)
Trisomy – one extra chromosome (2n +1)
Tetrasomy – two extra chromosomes (2n + 2)