Genetics yr 10

Question 1

DNA

Answer 1

Deoxyribonucleic acid molecule located in the nucleus of cells that contains the genetic information responsible for the development and function of an organism.

Question 2

Gene

Answer 2

A distinct sequence of nucleotides forming part of a chromosome which is a unit of heredity that is transferred from a parent to offspring.

Question 3

Chromosome

Answer 3

A threadlike structure of nucleic acids found in the nucleus of living cells, which carries genetic information in the form of genes.

Question 4

Cell division

Answer 4

The division of a cell into two daughter cells with the same genetic material. May be mitosis (clone copy) or meiosis (for reproduction).

Question 5

Gametes

Answer 5

Reproductive cells of plants and animals which are haploid because they contain only one set of chromosomes.

Question 6

Zygote

Answer 6

Fertilized egg cell that results from the union of a female gamete (egg or ovum) with a male gamete (sperm).

Question 7

Somatic cell

Answer 7

Cells of the body which do not include gametes. These are diploid because the contain two sets of chromosomes.

Question 8

Autosomes

Answer 8

All of the numbered chromosomes of the cell which do not include the sex chromosomes. These contain the bulk of the cell’s information required to function.

Question 9

Phenotype

Answer 9

An individual’s observable trait. This is determined by both their genomic makeup (genotype) and environmental factors.

Question 10

Homologous

Answer 10

Chromosomes which pair during replication and have the same structural features and patterns of genes.

Question 11

Trisomy

Answer 11

Three copies of a chromosome instead of the normal pair of two e.g. the addition of a number 21 chromosome that results in Down syndrome within each cell. Only one copy of a particular chromosome is monosomy.

Question 12

Karyotype

Answer 12

The number and general appearance (size, shape and banding) of a set of chromosomes in a somatic cell.

Question 13

Nucleotides

Answer 13

Compounds (DNA building blocks) containing a sugar part (deoxyribose or ribose), a phosphate part and a nitrogen-containing base that varies.

Question 14

Base-pair rule

Answer 14

The concept that in DNA every adenine (A) binds with a thymine (T), and every cytosine (C) binds to a guanine (G).

Question 15

Triplet

Answer 15

A sequence of three nucleotides in DNA that can code for one amino acid. E.g. the triplet base sequence CAA codes for the amino acid, valine.

Question 16

Diploid

Answer 16

The paired set of chromosomes within a somatic cell e.g. 23 mrs in each body cell. Sex cells have only one copy of each chromosome in the cell and this is referred to as the haploid number.

Question 17

Variation

Answer 17

Differences of characteristics shown in individuals due to various reasons. Inheritance of this variations or phenotypes may be favourable to increase chance of survival.

Question 18

Alleles

Answer 18

Alternative forms of a gene for a particular characteristic. Each allele is characterised by a slightly different nucleotide sequence.

Question 19

Homozygous

Answer 19

Having two identical alleles for a characteristic within the genotype.

Question 20

Heterozygous

Answer 20

Having two different alleles for a characteristic within the genotype.