mendel

Question 1

What is a cell?

Answer 1

The basic unit of all living things.

Question 2

what is the nucleus, what does it do and where is it found?

Answer 2

The ‘control centre’ of the cell found in all eukaryote cells. It contains the instructions for the metabolism of the cell, its growth and division – place where the codes to build proteins (genes) is located

Question 3

what is a chromosome

Answer 3

A strand of DNA, found in all living things, usually in the nucleus. All species have different numbers of chromosomes.

Question 4

what is DNA?

Answer 4

a self-replicating material that is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information

Question 5

what is autosomes?

Answer 5

Chromosome not involved in sex determination. Humans have two copies of each of the 22 different types of autosomes (44 in total)

Question 6

what is a sex chromosome?

Answer 6

Chromosomes involved in the determination of sex. Humans have two of these – one large chromosome X and a smaller Y. Normal females have two X chromosomes, a normal male has an X and Y.

Question 7

what is a karyotype?

Answer 7

A photo of the chromosomes in an individual where maternal and paternal chromosomes have been paired and arranged from largest to smallest – together with the sex chromosomes

Question 8

what is a homolygous chromosome?

Answer 8

A pair of matching (size, staining pattern, location of centromere) chromosomes containing the same genes, one of maternal origin and one of paternal origin.

Question 9

what is a somatic cell?

Answer 9

Body cell, contains two sets of each chromosome (one maternal and one paternal)

Question 10

what is mitosis?

Answer 10

Cell division in somatic cells for growth and repair. One diploid parent cell produces two identical diploid daughter cells.

Question 11

what is a diploid?

Answer 11

Two sets of chromosomes – one maternal one paternal in origin.

Question 12

what is meiosis?

Answer 12

Cell division in gonads to produce gametes. One diploid parent cell produces four non-identical haploid daughter cells called gametes – for reproduction.

Question 13

what is a gonad?

Answer 13

A general term for ovaries (female) and testes (male).

Question 14

what is a gamete?

Answer 14

A general name for ova or egg (female) and sperm (male).

Question 15

what is a haploid?

Answer 15

One complete set of chromosomes. Gametes are the only haploid cells in humans.

Question 16

what is a zygote?

Answer 16

A new cell produced by the fusion of ovum and sperm cells (fertilisation)

Question 17

what is a gene?

Answer 17

A section of DNA along a chromosome which codes for one inherited trait (protein). A gene is found on a particular chromosome at a particular place or locus.

Question 18

what is an allele?

Answer 18

One version or variety of a gene. One gene can have a number of different alleles which may exist at the same locus. Each individual carries 2 copies of each autosome and so 2 alleles – which may be the same or different. A gene located on the X chromosome is not found on the Y; therefore males only get one allele for an X-linked gene.

Question 19

what is a genotype?

Answer 19

The actual set of alleles for a gene present in an individual

Question 20

what is a phenotype?

Answer 20

The outward, physical expression of an individual – it is the end result of the interaction between the genotype and the environment

Question 21

what is an environment?

Answer 21

All factors affecting the growth and life of an individual – nutrition, light etc.

Question 22

what is a homozygous, give an example

Answer 22

Both alleles for the genotype are identical. E.g. AA or aa

Question 23

what is hetrozygous, give an example

Answer 23

Both alleles in the genotype are different. E.g. Aa

Question 24

what is a dominant allele?

Answer 24

A trait that is always expressed in the phenotype regardless if the individual is homozygous or heterozygous for a trait. Denoted by a capital letter in the genotype.

Question 25

what is a recessive allele?

Answer 25

A trait that is only expressed in the phenotype if it is the only allele present – i.e. homozygous. Denoted by a lower case letter in the genotype.

Question 26

what is a pedigree?

Answer 26

A diagram showing a family ‘tree’ with parents an offspring used to show the inheritance of a particular trait.

Question 27

what is the P generation?

Answer 27

The parental generation.

Question 28

what is the F1 generation?

Answer 28

The first generation produced by the parental generation.

Question 29

what is the F2 generation?

Answer 29

The second generation produced from crossing individuals of the F1

Question 30

what are the base pairs?

Answer 30

cytosine (C) and guanine (G), adenine (A) and thymine (T)

Question 31

why is it important for DNA to be able to self-replicate and carry information before cell replication?

Answer 31

Cells must replicate their DNA before they can divide. This ensures that each daughter cell gets a copy of the genome, and therefore, successful inheritance of genetic traits.