Summary
Summary Genetics & Genetic Engineering - Life Sciences
Summarised notes on Matric Genetics & Genetic Engineering from the Mind Action series Life Science textbook.
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Content preview
Genetics and Genetic EngineeringGenetics
A branch of biology that studies heredity and variation in organisms
Heredity: passing on of traits/characteristics from one generation to the next
Gregor Mendel
- Father of genetics : Austrian monk
- First major breakthrough in heredity by investigating the transfer of traits
- Discovery: ‘something’ (we know they are genes but he called them factors) is passed on through
offspring which are unique yet the same
- Published his work but not recognised until after he died and was accepted as Darwin’s theory was
Genes and Alleles
Genes
Chromatid: one, helical DNA molecule
DNA molecule: series of genes
Gene: section of DNA that controls a hereditary trait (the base unit of heredity)
- Each chromosome has between 100s & 1000s of genes. Total around 20k-25k
- Nearly all somatic cells w nuclei have an exact copy
- Each cell has two of each kind of gene before replication (maternal & paternal) AKA alleles
- Gene pool: set of all genes or genetic info in a population.
- Large: high genetic diversity and more chances of survival
- Small: low genetic diversity and more chances of extinction
Gene Activity
- Cells have a full complement of DNA but only useful ones for specific proteins are activated
- Some play a role only in development of embryo and are then inactive
- Housekeeping genes: active genes that make proteins
- Non-coding genes: 98% and occur between coding sections
Alleles
Genes responsible for controlling different versions of a trait found in the same locus on a homologous
chromosome
One of two or more forms of a gene
Representation: capital letter for dominant alleles, lower case for recessive alleles
, How alleles are passed on
By way of chromosomes in gametes that are made during meiosis
Summary
Somatic cells are diploid (2n) as they have:
- A pair of homologous chromosomes
- Two alleles which may be the same or different
Sex cells are haplloid (n) as they have:
- One pair of homologous chromosomes
- One of each pair of alleles
Gametes
Fertilisation: male and female gamete fuse each with their alleles to form diploid zygote
Divides by mitosis to form a new organism made up of cells with the same set of chromosomes and alleles as
zygote
Genotypes and Phenotypes
Genotype: made up of all the genes an organism carries on its chromosomes which are inherited
Phenotype: the physical appearance of an organism, partly programmed by genes but also by external factors
Homozygous and Heterozygous
A zygote will have 2 alleles for each gene (one from each parent) on the same locus of each chromosome of a
homologous pair
- Homozygous: pair of alleles at locus are the same
- Heterozygous: pair of alleles at locus are different
Dominant and recessive alleles
Dominant: trait that is expressed in the offspring
Recessive: trait that is suppressed in the presence of a dominant allele
There will be 3 genotypes yet 2 phenotypes because:
- If there is a dominant alleles the homozygous organism will have the same phenotype as the
heterozygous
- The recessive will only be expressed as the phenotype when there is no dominant allele present
(homozygous)
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller bonolomuvunyi. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R50,00. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73096 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy summaries for 15 years now