Module 3.3:
Genetics and genetic engineering
Glossary:
All words with ‘*’ can be found below, however, some definitions are found within the
text
Hereditary: Passing on of traits or characteristics from generation to generation
Gene: Section of DNA that contains hereditary characteristics
Somatic cells: Body cells
Allele: Genes responsible for controlling different versions of a trait found in the same
locus on homologous chromosomes
Gene pool: Set of genes/genetic information in a population of sexually producing
organisms
Housekeeping genes: Genes that are active in many cell types, making proteins
Non-coding genes: Do not code for proteins (between coding sections)
Hox genes: Master gene that determines the way that body develops a zygote
Epigenetic: Control of genes
Locus: Position
Dominant allele: Trait is expressed in offspring
Recessive allele: Trait is suppressed in offspring
Gamete: Sex cell
Diploid: Number of chromosomes is reduced from two sets in parent to one cell
Haploid: Gametes/spores formed with one set of chromosomes
Genotype: Made of all genes an organism carries on its chromosome (inherited)
Phenotype: Physical appearance of organism
Homozygous: Pair of alleles at a locus are the same in the organism
Heterozygous: Pair of alleles at a locus are different in the organism
Monohybrid cross: Cross between parents with different alleles of a single gene
Sex chromosome/gonosome: 23rd chromosome pair
Homogametic: Genotype XX
Heterogametic: Genotype XY
Gonad tissue: sex organ
X-linked genes/sex-linked alleles: Alleles carried on the non-homologous part of an X
chromosome
Polygenic inheritance: More than one pair of alleles responsible for a trait
Genome: Complete set of genetic instructions (genes) to create an organism
Family pedigree: A pattern of inheritance that shows genotypes and phenotypes of
several generations of individuals
, What is genetics?
- Branch of biology that studies heredity* and variation in organisms
- Explains both similarities and differences between parents and their offspring
‘Father of genetics’
- Gregory Mendel, an Austrian monk
- Responsible for the first major breakthrough in the study of heredity by
investigating the transfer of characteristics from one generation to the next
- Said ‘something’ (now known as DNA) was passed down through sexual
reproduction to create unique offspring, yet the same
Genes*
- Each chromatid is made of one helical DNA molecule, which is made up of a
series of genes
- A gene can be defined as a section of DNA (series of nucleotide bases) that
control a hereditary trait
- Each chromosome has between several hundred and several thousand genes
(total of 20 000 - 25 000 in a human)
- Nearly all somatic cells have an exact copy of all the genes in that organism
- Due to two types of chromosomes (paternal and maternal), each cell contains
two of each kind of gene before replication = aka alleles*
- A large gene pool* = high genetic diversity = high chance of survival
- A small gene pool = low genetic diversity = low chance of survival/extinction
- Only 1% of human DNA is unique from other species
How active are genes?
- Although each cell has a full set of genes, only the ones needed are activated
while the rest are suppressed. ∴different genes are activated in different
cells = specific proteins created giving each cell its own character (eg:
hair cell, brain cell etc.)
- Some genes play role in embryo then become inactive
- Housekeeping genes* are active in many cells, other genes are mostly inactive
- Most genes are non-coding* genes makeup 98% of genes
Alleles
Genetics and genetic engineering
Glossary:
All words with ‘*’ can be found below, however, some definitions are found within the
text
Hereditary: Passing on of traits or characteristics from generation to generation
Gene: Section of DNA that contains hereditary characteristics
Somatic cells: Body cells
Allele: Genes responsible for controlling different versions of a trait found in the same
locus on homologous chromosomes
Gene pool: Set of genes/genetic information in a population of sexually producing
organisms
Housekeeping genes: Genes that are active in many cell types, making proteins
Non-coding genes: Do not code for proteins (between coding sections)
Hox genes: Master gene that determines the way that body develops a zygote
Epigenetic: Control of genes
Locus: Position
Dominant allele: Trait is expressed in offspring
Recessive allele: Trait is suppressed in offspring
Gamete: Sex cell
Diploid: Number of chromosomes is reduced from two sets in parent to one cell
Haploid: Gametes/spores formed with one set of chromosomes
Genotype: Made of all genes an organism carries on its chromosome (inherited)
Phenotype: Physical appearance of organism
Homozygous: Pair of alleles at a locus are the same in the organism
Heterozygous: Pair of alleles at a locus are different in the organism
Monohybrid cross: Cross between parents with different alleles of a single gene
Sex chromosome/gonosome: 23rd chromosome pair
Homogametic: Genotype XX
Heterogametic: Genotype XY
Gonad tissue: sex organ
X-linked genes/sex-linked alleles: Alleles carried on the non-homologous part of an X
chromosome
Polygenic inheritance: More than one pair of alleles responsible for a trait
Genome: Complete set of genetic instructions (genes) to create an organism
Family pedigree: A pattern of inheritance that shows genotypes and phenotypes of
several generations of individuals
, What is genetics?
- Branch of biology that studies heredity* and variation in organisms
- Explains both similarities and differences between parents and their offspring
‘Father of genetics’
- Gregory Mendel, an Austrian monk
- Responsible for the first major breakthrough in the study of heredity by
investigating the transfer of characteristics from one generation to the next
- Said ‘something’ (now known as DNA) was passed down through sexual
reproduction to create unique offspring, yet the same
Genes*
- Each chromatid is made of one helical DNA molecule, which is made up of a
series of genes
- A gene can be defined as a section of DNA (series of nucleotide bases) that
control a hereditary trait
- Each chromosome has between several hundred and several thousand genes
(total of 20 000 - 25 000 in a human)
- Nearly all somatic cells have an exact copy of all the genes in that organism
- Due to two types of chromosomes (paternal and maternal), each cell contains
two of each kind of gene before replication = aka alleles*
- A large gene pool* = high genetic diversity = high chance of survival
- A small gene pool = low genetic diversity = low chance of survival/extinction
- Only 1% of human DNA is unique from other species
How active are genes?
- Although each cell has a full set of genes, only the ones needed are activated
while the rest are suppressed. ∴different genes are activated in different
cells = specific proteins created giving each cell its own character (eg:
hair cell, brain cell etc.)
- Some genes play role in embryo then become inactive
- Housekeeping genes* are active in many cells, other genes are mostly inactive
- Most genes are non-coding* genes makeup 98% of genes
Alleles
