Chromosomes, Genes, Alleles Ans Characteristics

Question 1

WHAT IS DNA?

Answer 1

Deoxyribonucleic acid (=DNA) is the molecule in the nucleus that carries our genetic code.

Question 2

FERTILISATION

Answer 2

EGG (Ovum) 23 chromosomes
SPERM 23 chromosomes
ZYGOTE 46 chromosomes in 23 pairs
EMBRYO 46 chromosomes in 23 pairs

Question 3

WHAT IS A CHROMOSOME?

Answer 3

A chromosome is a length of DNA
Chromosomes are arranged into pairs the nucleus.
Along the length of each chromosome coding regions called genes

Question 4

WHAT IS AN GENE?

Answer 4

Genes are small sections of chromosomes (DNA) that code for a particular characteristics. (Protein)
This sequence of amino acids makes a specific protein.

Question 5

WHAT IS AN ALLELE?

Answer 5

An allele is a diffrent/alternate form of a gene.
E.g. if the gene is eye colour the alleles could be:
Brown ellele
Blue allele
Green allele

Question 6

WHAT IS AN ALLELE?

Answer 6

• Homozygous alleles are two alleles that are the same. E.g. BB, TT, cc
• Heterozygous alleles are two alleles that are different. E.g. Bb, Tt,
Cc

Question 7

DOMINANT AND RECESSIVE ALLELES

Answer 7

• Dominant alleles are always expressed if they are
present.
• Recessive alleles are only expressed if there are 2
recessive alleles present.
• If an individual has 2 alleles the same (e.g. BB, tt etc)
this is called homozygous alleles.
• If an individual has 2 different alleles (e.g. Bb, Tt etc)
this is called heterozygous alleles

Question 8

ASEXUAL REPRODUCTION

Answer 8

Asexual reproduction is a method of reproducing without sex and therefore without sex cells (gametes). The simplest form of asexual reproduction is binary fission.

Question 9

SEXUAL REPRODUCTION

Answer 9

Sexual reproduction requires two individuals and the production and the production and fusion of sex cells (gametes). The gametes are produced by meiosis so there are several possible combinations of genetic information when the gamets fuse to create a new life.