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Introduction to Genetics PowerPoint Presentation

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Description : Check out this medical titled "Introduction to Genetics”.

This medical gives an introduction to genetics.

Genetics is the branch of biology that studies heredity, or the passing on of traits from one generation to the next. It deals with the molecular basis of inheritance and the variations in inherited traits. The study of genetics has contributed significantly to our understanding of many biological processes, including evolution, disease, and behavior.

The fundamental unit of heredity is the gene, which is a segment of DNA that contains the instructions for the production of a specific protein or RNA molecule. The human genome, or the complete set of genetic material in a human cell, consists of about 20,000-25,000 genes.

Genetic traits can be either dominant or recessive, meaning that they can either mask or be masked by other traits. In addition, genetic traits can be influenced by environmental factors, which can lead to variations in expression.

The study of genetics has many practical applications, including the diagnosis and treatment of genetic diseases, the development of genetically modified organisms, and the use of genetic testing in criminal investigations and ancestry research.

Tags : Genetics, inherited traits, heredity, gene, DNA, RNA molecule, Genetic traits, Medical Genetics, Medical Genetics

Published on : Jun 01, 2023 | Views : 973 | Downloads : 0

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Slide 1-

Gregor Mendel and his wacky peas Introduction to Genetics
Slide 2-

What is genetics? The scientific study of heredity
Slide 3-

Gregor Mendel Born in 1822 in Czechoslovakia. Became a monk at a monastery in 1843. Taught biology and had interests in statistics. Also studied at the University of Vienna
Slide 4-

Mendel continued Most famous for his work with pea plants Between 1856 and 1863 he grew and tested over 28,000 pea plants (That’s what he is contemplating so seriously in the picture)
Slide 5-

Why Peas? Easy to grow. Easily identifiable traits Trait – a specific characteristic Can work with large numbers of samples
Slide 6-

Mendel’s experiments The first thing Mendel did was create a “pure” plant or true-breeding plant. True breeding – If the parent repeatedly only produce offspring with the same trait For example: A plant true-breeding for purple flowers will always produce offspring with purple flowers.
Slide 7-

Mendel’s experiments What happens if you cross two plants which are true-breeding for contrasting traits??? purple flowers x white flowers wrinkled seeds x smooth seeds tall plants x short plants etc, etc, etc,
Slide 8-

Mendel’s experiments He always found the same pattern He discovered that even though one of the parent plants had white flowers, ALL of the offspring had purple flowers! True-breeding parents Hybrids
Slide 9-

Mendel’s experiments Mendel repeated this experiment with other traits, in every case, one trait “won out” For example: Purple flower color “won out” over white flower color. Smooth seed texture “won out” over wrinkled seed texture.
Slide 10-

Mendel’s experiments Mendel called the trait that “won out” in the offspring dominant (purple flowers) . He called the trait that dissappeared in the offspring recessive (white flowers) .
Slide 11-

Mendel’s experiments What would happen when Mendel let the offspring self-pollinate? Was the next generation true-breeding for the dominant trait? Would Mendel continue to see only purple flowers?
Slide 12-

No! The white flowers reappeared (about ¼)
Slide 13-

From his experiments, Mendel concluded two things Inheritance is determined by factors passed on from one generation to another. Today these “factors” are called genes, but Mendel knew nothing about chromosomes, genes or DNA because there terms hadn’t been identified yet Allele – difference forms of a gene
Slide 14-

From his experiments, Mendel concluded two things 2. Some alleles are dominant while other are recessive. An organism with a dominant allele for a trait will always express that allele. An organism with a recessive allele for a trait will express that form only when the dominant allele is not present.
Slide 15-

Which led him to create to “laws” of inheritance The Law of Segregation: Two factors (alleles) control each specific characteristic (gene). These factors (alleles) are separated during the formation of gametes (sex cells).
Slide 16-

Which led him to create to “laws” of inheritance 2. The Law of Independent Assortment: Factors (alleles) for different characteristics (genes) are distributed to gametes (sex cells) independently. This means that the allele for seed texture isn’t dependent on the allele for plant height, etc.
Slide 17-

Probability The likelihood of a particular event occurring. Can be expressed as a fraction, percent or ratio. The more trials performed, the closer the actual results to the expected outcomes.
Slide 18-

Punnett Square A diagram used to show the probability or chances of a certain trait being passed from one generation to another.
Slide 19-

Using a Punnett square Gametes are placed above and to the left of the square Offspring are placed in the square. Capital letters represent dominant alleles. (Y) Lower case letters represent recessive alleles. (y)
Slide 20-

Punnett square example In a cross between PP x Pp. What percent of the offspring would you expect to be purple? P = purple, p = white One parent goes here One parent goes here
Slide 21-

Let’s do another one… In a cross between Pp x Pp. What percent of the offspring would you expect to be white? P = purple, p = white
Slide 22-

Dominant – allele, which if present, will ALWAYS be expressed Represented by a capital letter, usually the first letter of the dominant trait Recessive – allele, which will only be expressed in the absence of a dominant allele Represented by a lowercase letter, the same letter as the dominant trait, just lowercase For example: Tall is dominant over short, T = tall, t = short Vocabulary
Slide 23-

Homozygous = when an organism has two identical alleles. YY or yy Heterozygous = when an organism has different alleles. Yy Vocabulary
Slide 24-

Genotype The genetic makeup Symbolized with letters For example: Tt or TT Phenotype Physical appearance of an organism Description of the trait For example: Tall, short, purple, white Vocabulary
Slide 25-

Some exceptions to Mendel’s principles: Some alleles are neither dominant nor recessive. Many traits are controlled by more than one gene (polygenic traits)
Slide 26-

Incomplete dominance A situation in which neither allele is dominant. When both alleles are present a “new” phenotype appears that is a blend of each allele. Alleles will be represented by capital letters only.
Slide 27-

Japanese four-o-clock flowers Red flower plant genotype = RR White flower plant genotype = WW Pink flower plant genotype = RW
Slide 28-

What happens when a red flower is crossed with a white flower? According to Mendel either some white and some red or all offspring either red or white. All are pink
Slide 29-

Codominance When two alleles both appear in the phenotype. Usually signified using superscripts. example: color of hair coat in cattle. crcr = red hairs cwcw = white hairs crcw = roan coat (mixture of both colors)
Slide 30-

Roan cattle inheritance
Slide 31-

Multiple allele inheritance When two or more alleles contribute to the phenotype. Human blood types: A,B,O and AB A and B are codominant to each other. Both A and B are dominant over O.
Slide 32-

How common are the different blood types? 45 % 40 % 11 % 4 %
Slide 33-

Polygenic traits Traits controlled by two or more genes. Examples: Human height, eye and skin color