Life Sciences: Life at Molecular, cellular, and tissue level
Strand 3
3.3: Genetics and genetic engineering
Genetics
Genes and Alleles
Genotypes and phenotypes
Homozygous and heterozygous
Sex Chromosomes
Sex-linked diseases
Gene mutations
Genomes
Genetic engineering
Genetics
What is genetics? -studies of heredity and the variations that occur
as genes passed on through various generations
Who was the ‘Father of Genetics’? Gregor Mendel
-responsible for the “somethings” breakthrough
-Mendel's findings were acce[ted like Charles
Darwin's findings
What are the ‘somethings”? These are genes that are a part of DNA molecules
in chromosomes
Genes and Alleles
Genes A gene is a section of DNA that controls a
hereditary characteristic
How active are genes? Only genes that are needed are activated at
different times of development.
, Alleles are genes responsible for controlling different
versions of a trait/ characteristic found in the same
locus on homologous chromosomes.
How are alleles represented? Represented by letters
Capital=dominant
lowercase=recessive
How are alleles passed from parent to offspring? By way of chromosomes in the gametes that are
made by the process of meiosis in the sex organ.
diploid= somatic cells, a pair of homologous
chromosomes
haploid=sex cells, one of a pair of homologous
chromosomes, one of each pair of alleles
What happens to the gametes? During fertilization, a male gamete fuses with a
female gamete to form diploid zygote
Genotypes and phenotypes
Genotype Made up of all the genes an organism carries on
its chromosomes which is has inherited from its
parents
Phenotype Is the physical appearance of an organism
Homozygous and heterozygous
If the pair of alleles at a locus are the same, the If the pair of alleles at a locus are different, the
organism is homozygous for that particular trait organism is heterozygous for that particular trait
Dominant and recessive alleles
Dominant Recessive
: the trait that is expressed in the organism : the trait is suppressed and not expressed in the
organism
Monohybrid crosses
A cross between parents with different alleles for a
single gene
Strand 3
3.3: Genetics and genetic engineering
Genetics
Genes and Alleles
Genotypes and phenotypes
Homozygous and heterozygous
Sex Chromosomes
Sex-linked diseases
Gene mutations
Genomes
Genetic engineering
Genetics
What is genetics? -studies of heredity and the variations that occur
as genes passed on through various generations
Who was the ‘Father of Genetics’? Gregor Mendel
-responsible for the “somethings” breakthrough
-Mendel's findings were acce[ted like Charles
Darwin's findings
What are the ‘somethings”? These are genes that are a part of DNA molecules
in chromosomes
Genes and Alleles
Genes A gene is a section of DNA that controls a
hereditary characteristic
How active are genes? Only genes that are needed are activated at
different times of development.
, Alleles are genes responsible for controlling different
versions of a trait/ characteristic found in the same
locus on homologous chromosomes.
How are alleles represented? Represented by letters
Capital=dominant
lowercase=recessive
How are alleles passed from parent to offspring? By way of chromosomes in the gametes that are
made by the process of meiosis in the sex organ.
diploid= somatic cells, a pair of homologous
chromosomes
haploid=sex cells, one of a pair of homologous
chromosomes, one of each pair of alleles
What happens to the gametes? During fertilization, a male gamete fuses with a
female gamete to form diploid zygote
Genotypes and phenotypes
Genotype Made up of all the genes an organism carries on
its chromosomes which is has inherited from its
parents
Phenotype Is the physical appearance of an organism
Homozygous and heterozygous
If the pair of alleles at a locus are the same, the If the pair of alleles at a locus are different, the
organism is homozygous for that particular trait organism is heterozygous for that particular trait
Dominant and recessive alleles
Dominant Recessive
: the trait that is expressed in the organism : the trait is suppressed and not expressed in the
organism
Monohybrid crosses
A cross between parents with different alleles for a
single gene
