Genes and chromosomes

Question 1

Structure of nucleotide

Answer 1

Phosphate group, deoxyribose sugar and nitrogen-containing base

Question 2

What are the four DNA bases and which pair with which

Answer 2

Adenine-thymine, cytosine-guanine

Question 3

What is the structure of DNA

Answer 3

the double helix tightly coiled around proteins called histones

Question 4

What are the dimensions of DNA coiling

Answer 4

the double helix tightly coiled around histones then coils further into super coils and another dimension of coiling enables DNA to be organised in chromosomes.

Question 5

What is the structure of a chromosome

Answer 5

two chromotides joined together at the centromere with kinetochore and telomeres at the end of each chromosome

Question 6

what are telomeres

Answer 6

a series of repeated bases at the end of each chromosome that protects the ends of the chromosomes

Question 7

what are alleles

Answer 7

forms or variations of the same gene

Question 8

where are genes located

Answer 8

alomst all human genes are present in the DNA of the cell nucleus. A small number of genes are present in the DNA of mitochondria (mtDNA) and chloroplasts (cpDNA)

Question 9

locus

Answer 9

plural: loci, the position of a gene on a chromosome

Question 10

what are genes on the same chromosome called

Answer 10

linked genes

Question 11

how are autosomes distinguished

Answer 11

their relative size, the position of the centromere which appears as a constriction along the chromosome and the patterns of light and dark banding that result from staining techniques

Question 12

what is it called when there is a extra or missing chromosome

Answer 12

aneuploidy

Question 13

when an organism is missing a chromosome

Answer 13

monosomy (2n-1)

Question 14

when an organism has one extra chromosome

Answer 14

trisonomy (2n+1)

Question 15

when an organism has two extra chromosomes

Answer 15

tetrasomy (2n+2)

Question 16

when an organism has an extra set of chromosomes

Answer 16

polyploidy

Question 17

cri-du-chat symptoms and cause

Answer 17

chromosome 5 deletion, mouth/facial malformations = distinct crying as an infant

Question 18

turners syndrome symptoms and cause

Answer 18

X0, one x chromosome is missing. short height, failure of ovaries to develop, heart defects

Question 19

klinefelter syndrome

Answer 19

XXY, extra X chromosome, tall, less muscular, broad hips, delayed puberty, less facial hair

Question 20

down syndrome cause and symptoms

Answer 20

trisomy 21, distinct eye shape, shorter stature, intellectual disability