Gregor Mendel - PowerPoint PPT Presentation

1 / 27
About This Presentation
Title:

Gregor Mendel

Description:

Gregor Mendel s Peas Gregor Mendel s Peas Genetics is the scientific study of heredity. Gregor Mendel was an Austrian monk. Mendel studied garden peas – PowerPoint PPT presentation

Number of Views:114
Avg rating:3.0/5.0
Slides: 28
Provided by: sanj198
Learn more at: https://www.sanjuan.edu
Category:

less

Transcript and Presenter's Notes

Title: Gregor Mendel


1
Gregor Mendels Peas
  • Gregor Mendels Peas
  • Genetics is the scientific study of heredity.
  • Gregor Mendel was an Austrian monk.
  • Mendel studied garden peas

2
Gregor Mendels Peas
  • Mendel knew that
  • the male part of each flower produces pollen,
    (containing sperm).
  • the female part of the flower produces egg cells.
  • Together they make a new plant

3
Gregor Mendels Peas
  • Pea flowers are self-pollinating. (Pollen can
    fertilize the flower it was made on)
  • Self-pollination results in the offspring getting
    all its DNA from 1 organism.

4
Gregor Mendels Peas
  • Mendel used True-Breeding Pea plants
  • Plants that were homozygous for a trait
  • To prevent Self pollination- Mendel removed
    either the male or the female parts from each
    flower.

5
Gregor Mendels Peas
  • Mendel took a brush and cross-pollinated the
    flowers by hand!
  • Mendel was able to produce seeds that had two
    different parents.

6
Genes and Dominance
  • Genes and Dominance
  • A trait is a specific characteristic that varies
    from one individual to another.

7
Genes and Dominance
  • Each original pair of plants is the P (parental)
    generation.
  • The offspring are called the F1, or first
    filial, generation.
  • The offspring of crosses between parents with
    different traits are called hybrids.
  • The F1 hybrid plants all had the character of
    only one of the parents.

8
Genes and Dominance
  • Genes and Dominance
  • Mendel studied seven pea plant traits, each with
    two contrasting characters.
  • He crossed plants with each of the seven
    contrasting characters and studied their
    offspring.

9
Genes and Dominance
Mendels F1 Crosses on Pea Plants
10
Genes and Dominance
Mendels Seven F1 Crosses on Pea Plants
Mendels F1 Crosses on Pea Plants
11
Genes and Dominance
  • Mendel's first conclusion was that biological
    inheritance is determined by factors that are
    passed from one generation to the next.
  • We call these factors GENES

12
Genes and Dominance
  • Mendel luckily chose traits controlled by a
    single gene with different forms.
  • The different forms of a gene are called
    alleles(ah-le-eels).

13
GENOTYPE vs PHENOTYPE
  • GENOTYPE are the actual DNA coded genes or
    instructions that make you.
  • PHENOTYPE The express or what the genotype
    looks like in the physical world. For short
    What you look like.

14
Genes and Dominance
  • The principle of dominance states that some
    alleles are dominant and others are recessive.

15
Genes and Dominance
  • Dominant alleles Only need one for this form to
    show in the phenotype Possible Genotype (DD or
    Dr)
  • Recessive Need two alleles for this one to show
    in the phenotype Possible Genotype (rr)

16
Segregation
  • Segregation
  • Mendel crossed the F1 generation with itself to
    produce the F2 (second filial) generation.
  • The traits controlled by recessive alleles
    reappeared in one fourth of the F2 plants.

17
Segregation
  • The reappearance of the trait controlled by the
    recessive allele indicated that at some point the
    allele for shortness had been separated, or
    segregated, from the allele for tallness.

18
Segregation
  • During the formation of GAMETES (sex cells)
    Alleles are separated (segregated) into different
    resulting daughter cells.

19
Segregation
  • Alleles separate during gamete formation.

20
Using a Punnett Square
21
What is a PUNNETT SQUARE?
  • A tool to predict the probability of certain
    traits in offspring that shows the different ways
    alleles can combine
  • A way to show phenotype genotype
  • A chart that shows all the possible combinations
    of alleles that can result when genes are crossed

22
What is a PUNNETT SQUARE?
  • Letters stand for dominant and recessive alleles
  • An uppercase letter stands for a dominant allele
  • Lowercase letters stand for recessive alleles

23
Using a PUNNETT SQUARE
  • To set up a Punnett square, draw a large square,
    and then divide it into 4 equal sections (also
    squares). It should look something like this

24
Using a PUNNETT SQUARE
  • Now you need two parents to mate, ones with a
    known genotype
  • For example, a red flower (genotype Rr) and a
    white flower (genotype rr). Rr x rr

25
Using a PUNNETT SQUARE
  • Place one of the parents on top, and one on the
    left. You should get a something similar to
    this

26
Using a PUNNETT SQUARE
  • Finally, take each letter in each column and
    combine it with each letter from each row in the
    corresponding square. You should now have a
    picture close to this

27
Using a PUNNETT SQUARE
  • The two-letter combinations are the possible
    genotypes of offspring
  • They are Rr, Rr, rr, and rr genotypes
  • From this it is possible to determine the
    probability (chance) that a flower will have a
    red phenotype (2/4 or 50) or a white phenotype
    (2/4 or 50)
Write a Comment
User Comments (0)
About PowerShow.com