Transcript unit 5 types of reproduction and meiosis

TYPES OF REPRODUCTION AND
MEIOSIS
UNIT 5: Chapter 11
TYPES OF REPRODUCTION
Asexual Reproduction does not include
joining of gametes
SPORES are asexual because they do
not have to fuse to another cell.
BUD becomes new
individual
FRAGMENTATION: Pieces of
organism develop into a new
whole organism (Starfish and
planarian are examples)
Hydra
BINARY FISSION:
Individual divides to
produce new offspring
Bacteria
PARTHENOGENESIS:unfertilized eggs
develop into individuals (some fish,
several insects, few species of frogs
and lizards)
Sexual Reproduction
Process of sexual reproduction in which male and
female gametes join to form a new cell (zygote).
Gametes are called sex cells.
Sexual versus Asexual Reproduction
Sexual
• GAMETES fuse to form
zygote
• VARIED GENES are
produced
• Genetic VARIATION
allows for greater
ADAPTATION in
changing environment
Asexual
• NO FUSION of gametes
• Very little GENETIC
variation
• MANY OFFSPRING in short
time without having to
find mate
• LESS genetic variation
causes LESS ability to
ADAPT to changing
environment
When gametes (egg and sperm) unite during
fertilization, each gamete contributes one
allele.
Meiosis
gametes
DRAW AND LABEL A
CHROMOSOME
Identical chromatids
centromere
chromatid
Chromosome
• DNA strands coiled around proteins
• Formed during cell division
• Contains specific genes on each
chromosome
• Found only in nucleus of cell
• Diploid organisms have 2 of each
chromosome, one from each parent
• Haploid organisms have one of each
chromosome
• Somatic chromosomes are in
different sizes and shapes
• Number if chromosomes are
different for each species
– Humans: 46 (23 pairs)
• Sex chromosomes ore either X or Y.
– Females receive XX
– males receive XY
Identical
Chromatids
Centromere
chromatid
What is a chromosome?
Formation of chromosome
Tightly coiled strands form chromosome
DNA/Protein strands coil tightly
DNA strands wrap around proteins
DNA = twisted ladder of nucleotides
Where are chromosomes found?
• Chromosomes are found in
the nucleus of our eukaryotic
cells.
• Many organisms have a different numbers of
chromosomes in their cells
– Fruit fly 4 chromosomes
– human 46 chromosomes
What are gametes?
• Also known as a sex cell.
\
– 23 chromosomes in sperm (male gamete).
– 23 chromosomes in egg (female gamete).
• Gametes are a product of meiosis.
• Meiosis is the process which the number of
chromosomes cell is cut in half through the
separation of homologous chromosomes.
– 2 part process.
– Process results in 4 gametes.
MEIOSIS
Meiosis
Meiosis- The process of cell division in sexually reproducing
organisms that reduces the number of chromosomes in
reproductive cells from diploid to haploid, leading to the
production of gametes in animals and spores in plants.
Meiosis
• Two phases of cell division (Meiosis 1 and 2)
• Produces cells with half the number of
chromosomes (Haploid)
– Haploid cells have one of each chromosome
– Haploid cells (sperm and egg) join to form zygote
• Meiosis allows genetic variation
– Joining of gametes makes new combinations of
genes for each new individual
Meiosis
Law of independent
assortment
Alleles of different genes
separate independently
of one another
PpTt
meiosis
pT
PT
Pt
pt
4 haploid gametes: one of each chromosome
Meiosis summary: Produces 4 haploid cells
Homologous chromosomes
•Same shape
•Same size
•Same type of genes
•One from each parent
One chromosome from each parent
Crossing over occurs during Prophase I
New genetic combination
•creates new combination of genes
•occurs between two homologous chromosomes
Gametogenesis: Process of making gametes
Most of cytoplasm from three cells
is combined into one egg cell
When Meiosis Goes Bad…..
http://www.infertilityivfhouston.com/images/Sperm-morphology.jpg
Dangers of gametes without 23
chromosomes….
Mitosis vs. meiosis
What is a karyotype?
A karyotype is a set of photographed
chromosomes grouped by pairs.
How is sex determined? Video
CHROMOSOME
PAIR ARE CALLED
SEX CHROMOSOMES:
IF XX= FEMALE
IF XY= MALE
AUTOSOMES
Chromosomes #122 are called
HUMAN MALE KAROTYPE
HUMAN FEMALE KARYOTYPE
What happens if there are 3
chromosomes on your 21
chromosome?
ANSWER: DOWN SYNDROME
Down Syndrome
Homologous chromosomes
•Same shape
•Same size
•Same type of genes
•One from each parent
One chromosome from each parent
Which letter is an example of meiosis?
Which letter is an example of
fertilization?
Letter A is an example of meiosis. Letter B is an example of fertilization.
DNA/Chromosomal Mutations
Chromosomal Mutations
Section 12-4
Deletion
Duplication
Inversion
Translocation
Genetic Mutation?
Genetic Mutation?
IS albinism caused by a genetic
mutation?
•
Albinism (from Latin albus, meaning "white") is a lack of pigmentation in the eyes,
skin and hair. It is an inherited condition resulting from the combination of
recessive genes passed from both parents of an individual. This condition is known
to affect mammals, fish, birds, reptiles, and amphibians.
Caused by a genetic mutation?
World’s Largest Feline
Is the caused by a genetic mutation?
• A clubfoot is a common birth defect.
Down Syndrome
• Defect (extra chromo) on the 21st
chromosome.
If someone has a defect or disease,
there is something wrong with
chromosomes in nucleus.
DISEASES
Can be caused by 2 things:
1. The environment that surrounds you.
2. Your inherited genes .
http://www.youtube.com/watch?v=kBfWyb
m0218&feature=related
(vytorin commercial)
What disorders are sex-linked?
• Baldness
• Hemophilia (free bleeder)
• Duchenne Muscular Dystrophy (Progressive
loss of muscle)
• Red-green colorblindness
These disorders are only found on the 23rd (sex)
chromosomes.
Colorblindness
• Are you color blind?
What disorders are autosomal?
Recall, alleles are different forms of genes.
• Disorders caused by recessive alleles: albinism, cystic
fibrosis, galactosemia, phenylketonuria(PKU), TaySachs disease
• Disorders caused by dominant alleles:
achondroplasia, huntington’s disease,
hyperchlesterolemia
• Disorders caused by codominant genes: sickle cell
anemia
Recessive Disorders
• Sickle Cell anemia (abnormal hemoglobin molecules
– Results in poor blood circulation
• Tay-Sachs Disease (defective form of a brain enzyme)
– Results in deterioration of nervous system in infants- early
death
• Cystic Fibrosis (Defective chloride-ion transport
protein)
– Excessive mucous accumulation in organs, especially lungsdie young
Environmental Influences on Traits
• Hydrangea flower color is due to amount of acid in
soil
• Temperature affects changes in fox color from winter
to summer
• Darker parts of Siamese cat are a lower temperature,
e.g., ears, nose, paws and tail
• Height in humans is influenced by temperature, such
as internal environmental condition.
Pedigree Chart
Normal female
Affected female
Carrier female
Normal male
Reading pedigree charts:
•If both males and females have disorder,
then trait is autosomal (on other
chromosomes)
•If trait shows up mostly in males, then trait
is sex-linked (on the X chromosome)
Affected male
parents
Children in birth order