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)
What is Karyotype?
It is the number and general appearance (size, shape and banding) of a set of chromosomes in a somatic cell
What is Telomere?
It is a cap of DNA on the tip of a chromosome that enables DNA to be replicated safely without losing valuable information
What is a telomerase?
It is an enzyme involved in maintaining and repairing a telomere
What is an Albino?
An organism which lacks pigment in skin, feathers, hair eyes etc.
What are Alleles?
A pair of genes located at corresponding positions in the homologous chromosomes. Alternatives in inheritance.
What is Artificial insemination ?
Is used to fertilise eggs.
Sperm is collected, stored and injected into the females, when required. Eggs may also be collected and artificially fertilised.
What is Co-dominance?
It occurred when 2 different alleles for the same characteristic are both fully expressed in the individual’s appearance
Eg, coat colour in cattle- rain cattle have both red and white hairs
What is Sex linked?
This occurred when a Characteristic is located on one of the sex chromosomes, usually the X chromosome in humans. Such characteristics occurs much more commonly in one sex than in the other ( makes in humans usually )
What is Recessive?
A gene which on,y appears on,h in the phenotype of a pure breeding (homozygous) organism. In hybrid organisms recessive genes are masked by the dominant gene.
What is Probability?
The change or liklihood of something occurring. Can be expressed as a fraction, a percent or a decimal between zero and one.
What is a pedigree ?
A family tree
A chart designed to relationships between individuals. Used to study patterns of inheritance,
What is a Mutation?
A permanent inheritable change in a gene or chromosome.
What is a mutant?
An organism which shows a mutation in its phenotype.
What is a monohybrid cross?
A breeding exercise in which the expression of a single characteristic is traced through 2 generations
What us Incomplete Dominance?
The interaction between 2 allele which produces a phenotype intermediate between 2 pure bred phenotypes. Eg red and white carnations will produce pink carnations
What is homozygous?
Pure breeding
Refers to an organism which contains the same genes for the determination of a specific characteristic.
What is Heterozygous?
Hybrid
An organism which contains 2 different genes for the determination of a specific characteristic.
What is a haploid number?
Haploid describes a cell that contains a single set of chromosomes. The term haploid can also refer to the number of chromosomes in egg or sperm cells, which are also called gametes. In humans, gametes are haploid cells that contain 23 chromosomes, each of which a one of a chromosome pair that exists in diplod cells.
What us a gene pool?
The total of all the genes available within in a specific population.
What is genetic engineering?
The intentional alteration of the genetic constitution of an organism by the substitution or addition of new genetic material.
What is F1?
First filial generation resulting in the cross of 2 parental organisms.
What is F2?
Second filial generation resulting from the cross of 2 F1 organisms.
What are Nucleotides?
They are compounds (DNA building blocks) containing a sugar part (deoxyribose or ribose), a phosphate part and a nitrogen-containing base that varies
What is deoxyribose?
It is the sugar in the nucleotides that make up DNA
What is Adenine?
It is a purine nucleobase that binds to thymine in DNA
What is Thymine?
It is a pyrimidine nucleobase that binds to adenine in DNA
What is Guanine?
It is a purine nucleobase that binds to cytosine in DNA. Also found in guano.
What is Cytosine?
It is a pyrimidine nucleobase that binds to guanine in DNA
What is the Base pairing rule?
It is the concept that in DNA every adenine (A) binds to a thymine (T), and every cytosine (C) binds to a guanine (G).
Also known as Chargaff’s rule.
Define Nucleic Acid :
Nucleic acids are molecules composed of building blocks called nucleotides, which are linked together in a chain
Why are Nitrogenous Bases
Nitrogenous base are adenine, thymine, cytosine, guanine and uracil are examples of nitrogenous bases that may be found in nucleotides.
What is a Double Helix?
DNA molecules have the appearance of a spiral ladder or double helix, a sugar–phosphate backbone or frame, and rungs or steps that are made up of nitrogenous bases joined together by hydrogen bonds.
What are complementary Base pairs?
Complementary base pairs are in DNA, specific base pairs will form between the nitrogenous bases adenine (A) and thymine (T) and between the bases cytosine (C) and guanine (G).
