Transcript Genetics II (4.4 & 4.5)

Genetics II
Abnormal Meiosis
Nondisjunction Disorders
Cytoplasmic Inheritance
Let’s review some genetics
terms…
Genetics Terms…
Our body cells are also known as:
A. somatic cells
B. gametes
Genetics Terms…
Our body cells are also known as:
A. somatic cells
B. gametes
Genetics Terms…
Sperm and egg cells are:
A. somatic cells
B. gametes
Genetics Terms…
Sperm and egg cells are:
A. somatic cells
B. gametes
Genetics Terms…
Examples of human somatic cells are:
A. skin cells, bone cells, nerve cells
B. sperm cells, egg cells
Genetics Terms…
Examples of human somatic cells are:
A. skin cells, bone cells, nerve cells
B. sperm cells, egg cells
Genetics Terms…
Somatic cells are diploid, which means…
A. They divide very quickly.
B. They have two sets of
chromosomes.
C. They have one set of chromosomes.
Genetics Terms…
Somatic cells are diploid, which means…
A. They divide very quickly.
B. They have two sets of
chromosomes.
C. They have one set of chromosomes.
Genetics Terms…
Which of the following is true?
A. Gametes are haploid.
B. Gametes are diploid.
C. Gametes are reproductive cells.
D. Two of the above are true.
Genetics Terms…
Which of the following is true?
A. Gametes are haploid.
B. Gametes are diploid.
C. Gametes are reproductive cells.
D. Two of the above are true.
Genetics Terms…
Which of the following is true?
Homologous chromosomes…
A. are similar in size and shape
B. are found in gametes
C. are found in somatic cells
D. separate during Anaphase II
E. Two of the above are true.
Genetics Terms…
Which of the following is true?
Homologous chromosomes…
A. are similar in size and shape
B. are found in gametes
C. are found in somatic cells
D. separate during Anaphase II
E. Two of the above are true.
Now let’s look at meiosis
again…
What kinds of errors can
happen during meiosis?
Nondisjunction
• can happen during Anaphase I or
during Anaphase II
• results in gametes can have too many
or too few chromosomes
• can also happen in mitosis, but this is
less harmful because it isn’t passed on
to the next generation
Chromosomal Disorders
• wrong number of
chromosomes
or
• changes
(mutations) in the
genetic
information
Karyotype - male or female?
Karyotype - male or female?
Down syndrome (trisomy 21)
Down Syndrome
•
•
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•
affects about 1 in 800 babies
varying degrees of intellectual disability
characteristic facial features
often have heart defects and other
problems
Trisomy 13
Trisomy 18
Trisomy 13 & Trisomy 18
• 1 in 16000 babies are born with
trisomy 13 and 1 in 5000 are born with
trisomy 18
• severe intellectual disabilities
• many physical birth defects
• most affected babies die before their
first birthday
Klinefelter syndrome
Klinefelter syndrome
• affects about 1 in 500-1000 boys
• usually have normal intelligence but
many have learning problems
• as adults they produce less than normal
amounts of testosterone and are
infertile
Turner syndrome
Turner syndrome (monosomy 23)
• affects 1 in 2500 girls
• usually infertile and do not undergo
normal puberty changes unless they are
treated with hormones
• some have health problems including
heart and kidney defects
• normal intelligence but some have
learning difficulties
Triple X
Triple X
• affects 1 in 1000 females
• usually no physical birth defects,
experience normal puberty and are
fertile
• usually have normal intelligence but
many have learning problems
XYY
XYY
• affects 1 in 1000 males
• sometimes taller than average, have
normal sexual development and are
fertile
• most have normal intelligence, though
some have learning, behavioral and
speech/language problems
Assisted Reproductive
Technologies (ARTs)
ARTs
• in vitro fertilization (IVF)
• artificial insemination
Applications & Implications
• animal breeding & wildlife conservation
• many benefits to using artificial
insemination
• cost?
Cytoplasmic Inheritance
Cytoplasmic DNA
• DNA in mitochondria and chloroplasts
• When a sperm cell fertilizes an egg cell,
which cell contributes the cytoplasmic
DNA?
• maternal inheritance
• paternal inheritance (less common)
Genetic Variation - Plants
• normal green
chloroplasts
• white chloroplasts
with genetic
mutation
Genetic Variation - Humans
• some rare genetic
disorders caused
by mutations in
mitochondrial
DNA
• DNA egg
swapping
Horizontal Gene Transfer