Chapter 2 - Genetics Flashcards
Define DNA?
Deoxyribonucleic acid
The chemical substance found in all living things that encodes the genetic information of an organism. DNA is composed of building blocks called nucleotides, which are linked together in a chain.
Define Gene:
A segment of a DNA molecule with a coded set of instructions in its base sequence for a specific protein product; when expressed, may determine the characteristics of an organism.
Define nucleus:
The control centre of a cell, chromosomes are found in here.
Define Chromosomes:
A tiny thread-like structures inside the nucleus of a cell. Chromosomes contain the DNA that carries genetic information.
What is Mitosis:
A cell division process that results in new genetically identical cells with the same number of chromosomes as the original cell
What is Cell Division?
It is a process that results in the production of new cells
What is Meiosis?
A cell division process that results in new cells with half the number of chromosomes of the original cell
What are Gametes?
They are reproductive or sex cells such as sperm or ova.
What is an Ova?
Is a female gametes or sex cells. Singular: ovum.
What is a sperm?
It is a male reproductive cell. It consists of a head, a middle section and a tail (flagellum) used to swim towards the ovum (egg).
What is fertilisation?
It is the penetration of the ovum by a sperm
What is a Zygote?
A formed by the fusion of male and female reproductive cells
What are somatic cells?
They are cells of the body that are not sex cells
What is a Genotype?
Genetic instructions (contained in DNA) inherited from parents at a particular gene locus
What is a phenotypes?
They are characteristics that result from the expression of an organism’s genotype. Phenotype depends on both the genotype and the environment.
What is an environment?
the living and non-living things in a particular place at a particular time; that is, the surroundings of a living thing
What are autosomes?
They are non-sex chromosomes
What is homologous?
It is used to describe members of each matching pair of chromosomes
What is non-homologous?
It is used to describe chromosomes that do not match
What are sex chromosomes?
They are chromosomes that differ in males and females in a species. In humans, for example, females contain two X chromosomes whereas males contain an X and a Y chromosome.
What is Trisomy?
It is where there are three copies of a chromosome instead of the normal pair of two, e.g. the addition of a number 21
21
chromosome that results in Down syndrome within each cell
What is monosomy?
It is a condition in which there is only one copy of a particular chromosome (rather than two) in a cell, e.g. Turner’s syndrome, which results in only one sex chromosome (XO)