Transcript BB - Effingham County Schools

Reproduction and Genetics
Two Types of Reproduction
Asexual Reproduction
• _________________Only one parent and
genetic material is identical to parent.
Sexual Reproduction
• __________________- Two parents and
offspring receives genes from both parents.
Asexual Reproduction
Binary Fission- asexual reproduction that occurs
in single celled organisms in which genetic
material is copied and one cell divides into two
identical daughter cells. EX: Bacteria
reproduce this way, and Yeast
Asexual Reproduction
Budding- an organism grows a part of of its
main body and this new growth eventually
breaks off to become a new organism. Ex:
Hydra (simple animal similar to jelly fish)
Asexual Reproduction
Fragmentation- Fragmentation is a form of asexual
reproduction where a new organism grows from a
fragment of the parent. Each fragment develops
into a mature, fully grown individual. Ex:
Starfish, and some fungi.
Sexual Reproduction
• Sexual Reproduction- Type of reproduction in
which male and female reproductive cells combine
to form new offspring with genetic material from
both parents.
***Offspring has genetic material from each parent which
creates- Offspring is NOT identical to parent!
Sexual Reproduction - Variation
Female Gamete
Male Gamete
23
Chromosomes
23
Chromosomes
46
Chromosomes
Sexual Reproduction - Variation
Female Gamete
Male Gamete
23
Chromosomes
23
Chromosomes
46
Chromosomes
Asexual Reproduction
Disadvantages
Advantages
Sexual Reproduction
Selective Breeding
• When humans select organisms for breeding
to get desirable traits.
Breeding
chickens that
lay the most
eggs
1.
Gregor Mendel – was an Austrian monk born in 1822 who
is known as the “father of genetics”
Genetics – the scientific study of heredity
Heredity – the passing of traits from parents to offspring
a. Traits are inherited by parents passing alleles to
their offspring (1 allele from dad & 1 allele from
mom)
a. Allele= different forms of the same gene
(ex: eye color = gene; brown eyes= allele,
blue eyes= allele
b. Some alleles are dominant (R) and some are recessive
(r)
• Dominant – will always express its form of a trait
when present
• Recessive – will only express its form of a trait when
the dominant allele is not present.
Genotypes
• Homozygous (rr, RR) SAME ALLELES
• Heterozygous (Rr) – dominant trait always shows.
DIFFERENT ALLELES
Remember: DNA is
found in the nucleus. It
is organized into a
chromosome before it
is copied.
Genes are located
on chromosomes!!
Sex cells (gametes)
are produced by
meiosis and have half
the number of
chromosomes
(haploid)
For every Gene or trait, an
2
individual gets ____
alleles
Alleles
DOMINANT
____________
alleles are represented by a capital
letter and are expressed even if one is present in
the genotype.
(Ex: BB= brown eyes, Bb= brown eyes)
RECESSIVE
___________
alleles are represented by a lower case
letter, and are only expressed if the dominant allele
in not present. (Ex: bb= blue eyes)
Vocabulary
______________is
Genotype
the combination of alleles
BB
bb
Bb
Phenotype
_______________
is the trait that is expressed
Brown eyes
Blue Eyes
Give the name of the Genotype
Homozygous Dominant
If both alleles are dominant (BB), we call this ____________
Brown Eyes
The phenotype will be _____________________
Homozygous Recessive
If both alleles are recessive (bb), we call this _________________
The phenotype will be ________________
Blue Eyes
If one allele is dominant and the other is recessive (Bb), we call thisHeterozygous
__________
Brown Eyes
The phenotype will be _________________
Name the Genotype
Bb=
bb=
BB=
Heterozygous
Homozygous Recessive
Homozygous Dominant
Give me the genotype or
genotypes possible for the
following phenotypes
Brown Eyes =
Blue Eyes =
BB or Bb
bb
Brown eyes (B) is dominant to
blue eyes (b)
Cross a heterozygous
brown eyed man with a
blue eyed woman.
B
b
b
Bb
bb
Bb
bb
Bb
bb
________
X ________
b
2:2
Phenotypic Ratio __________
2:2
Genotypic Ratio ____________
Brown eyes (B) is dominant to
blue eyes (b)
Cross a heterozygous
brown eyed man with a
blue eyed woman.
B
b
B
BB
Bb
b
Bb
bb
Bb
Bb
________
X ________
1:2:1
Phenotypic Ratio __________
3:1
Genotypic Ratio ____________