Genetic Basics

Microbiology

Genetic Basics

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Overview

Genetics Vocab
1. Genes- sections of DNA that code for protein
2. Genotype- inherited paired alleles that determines phenotype
3. Phenotype-the physical expression of a trait
4. Allele-A single copy of a specific gene
Mendel’s Discoveries
1. Law of Dominance- dominant genes mask recessive alleles
  1. AA, Aa same phenotype
2. Law of segregation- Alleles can seperate and combine as either
  1. Homozygous (same alleles) AA, aa
  2. Heterozygous (different alleles) Aa
3. Law of independent Assortment- traits are not linked and can recombine
  1. Punnett squares- used to predict genetic outcomes of offspring
    1. monohybrid cross- follow one trait
    2. dihybrid cross- follow 2 traits at once

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Transcript

Today we are going to briefly discuss the basics of genetics.

So in genetics vocab is key to understanding. SO DNA has specific areas that code for proteins, those areas are called genes. And you cells have 2 copies of every gene One from mom and the other from dad. that individual copy of a gene is known as an allele. So our alleles are paired up and together they are called our genotype for any given trait. And that genotype is ultimately what determines the expression of that trait and how it acts/looks… this is said to be out phenotype. Your Genotype determines you phenotype. So in this image we can see examples of genotypes (letter symbols and the phenotype here is flower color.)

So when these alleles pair up, their expression can be impacted by different combinations or versions of a gene. To keep it simple Gregor was a monk who studied basic inherited traits of pea plants. One trait was typically dominant over the other when paired. Purple dom over white. So here you can see two combinations give rise to purple flowers. BB or Bb. This is the law of dominance. In order for white the recessive trait to appear you need two copies of the recessive gene (bb).

And because these traits separate from one another during meiosis they can the recombine it a different way. Either Homozygous two the same or heterozygous 2 different.

The law of independent assortment revealed that traits are not linked… so you can have different combinations of traits in a gamete. And then to predict the outcome of those combinations you can use a Punnett square like the one here to determine to odds of an offspring inheriting a particular trait.

In summary….. Genes can have different versions of alleles. Your genotype determines your phenotype. Alleles can pair as homozygous or heterozygous. Dominant traits present usually mask recessive traits and Punnett square help us determine the odds of a have offspring with certain traits.

Thank you for reviewing the basics of genetics today. Go out and be your best self and happy nursing.