UNIT 4 WARM UPS
Meiosis and Heredity
10/10 – BIO Warm UPs
1.
2.
When are mutations most likely to occur?
Are mutations random or planned?
10/10 – BIO Warm UPs
When are mutations most likely to occur?
1.
1.
Most occur during meiosis or mitosis – whenever the DNA
is replicated for cell division
Are mutations random or planned?
2.
1.
Mutations are random changes in the DNA
10/11 – BIO Warm UPs
1. Explain why some people are lactose tolerant and
some people are lactose intolerant.
10/11 – BIO Warm UPs
1.
Explain why some people are lactose tolerant and
some people are lactose intolerant.
1.
Humans normally lose the ability to digest lactose (they
stop making the enzyme lactase) as they get older
because only babies need to digest milk. In Europe and
Africa mutations occurred that allowed some people to
continue to make the enzyme lactase as adults. These
people became lactose tolerant. People who were
lactose tolerant were more likely to survive droughts
and other hardships, so this gene became more common
in these regions.
10/12 – BIO Warm UPs
1.
2.
3.
What is the difference between homologous
chromosomes and sister chromatids?
In what stage of meiosis do homologous
chromosomes separate?
In what stage of meiosis do sister chromatids
separate?
10/12 – BIO Warm UPs
1.
What is the difference between homologous
chromosomes and sister chromatids?
1.
2.
3.
Homologous chromosomes are similar but not identical. Each
carries the same genes in the same order, but the alleles for each
trait may not be the same. One chromosome of each
homologous pair comes from the mother and one comes from the
father. Sister chromatids are identical copies of a chromosome.
When chromosomes replicate in S phase, they form sister
chromatids.
In what stage of meiosis do homologous chromosomes
separate? Meiosis I
In what stage of meiosis do sister chromatids separate?
Meiosis II
10/13 – BIO Warm UPs
1.
2.
Explain the difference between diploid and haploid.
At what stage in meiosis do the cells become
haploid?
10/13 – BIO Warm UPs
Explain the difference between diploid and haploid.
1.
1.
2.
Diploid cells contain two complete sets of chromosomes,
one from each parent.
Haploid cells contain one set of chromosomes. Gametes
or sex cells (sperm and egg) are all haploid.
At what stage in meiosis do the cells become
haploid?
2.
1.
Cells become haploid after telophase I in meiosis I.
Diploid vs Haploid
X
y
y
Prophase I
y
X
X
y
Cytokinesis
X
y
X
Metaphase I
Anaphase I
Telophase I
y
y
y
Prophase II
Metaphase II
y
y
Telophase II
and
Anaphase II
Cytokinesis
y
X
X
X
X
X
X
10/14 – BIO Warm UPs
What is crossing over? In what part of meiosis does
it occur?
2. What is independent assortment? In what part of
meiosis does it occur?
3. If diploid cell with 10 chromosomes undergoes
meiosis to form gametes, how many chromosomes
will each gamete have? Are the gametes haploid or
diploid?
* Gametes are sex cells (sperm and egg)
1.
10/14 – BIO Warm UPs
What is crossing over? In what part of meiosis does it
occur?
1.
1.
Homologous chromosomes swap genes. It occurs in prophase 1
of meiosis 1.
What is independent assortment? In what part of meiosis
does it occur?
2.
1.
Homologous chromosomes line up randomly during metaphase
1 of meiosis 1.
If diploid cell with 10 chromosomes undergoes meiosis to
form gametes (sex cells – sperm and egg), how many
chromosomes will each gamete have? Are the gametes
haploid or diploid?
3.
1.
Each gamete will have 5 chromosomes. They are haploid.
10/17 – BIO Warm UPs
1.
2.
What is the difference between phenotype and
genotype?
What is the difference between homozygous and
heterozygous?
10/17 – BIO Warm UPs
1.
What is the difference between phenotype and
genotype?
1.
2.
Genotype is the combination of alleles. Phenotype is the
physical trait that is determined by the genotype.
What is the difference between homozygous and
heterozygous?
1.
Homozygous has two of the same alleles (TT or tt).
Heterozygous has two different alleles (Tt).
10/18 – BIO Warm UPs
1.
Purple flowers (B) are dominant to white flowers (b).
Cross two plants that are heterozygous for purple
flowers.
1.
2.
3.
Draw the Punnett Square
What is the genotypic ratio for the offspring?
What is the phenotypic ratio of the offspring?
10/18 – BIO Warm UPs
1.
Purple flowers (B) are dominant to white flowers (b).
Cross two plants that are heterozygous for purple
flowers.
Draw the Punnett Square
2.
What is the genotypic ratio
for the offspring?
¼ BB: ½ Bb: ¼ bb
3. What is the phenotypic ratio
of the offspring?
¾ Purple flowers: ¼ White flowers
1.
10/19 – BIO Warm UPs
1.
2.
A woman with a genotype of IAi has children with a man
with a genotype IBi. What are the genotypic and phenotypic
ratios for their offspring?
Are these examples of codominance or incomplete
dominance:
1. A horse can have three possible phenotypes: Black (BB),
White (WW) or Gray (BW).
2. A flower can be Yellow (CYCY),
White (CW CW) or Yellow and
White (CW CY)
10/19 – BIO Warm UPs
1.
2.
A woman with a genotype of IAi has children with a
man with a genotype IBi. What are the genotypic and
phenotypic ratios for their offspring?
Genotypic: ¼ IAIB : ¼ IAi : ¼ IBi : ¼ ii
Phenotypic: ¼ Type AB: ¼ Type A: ¼ Type B: ¼ Type O
Are these examples of codominance or incomplete
dominance:
1. A horse can have three possible phenotypes: Black
(BB), White (WW) or Gray (BW). Incomplete Dominance
2. A flower can be Yellow (CYCY), White (CW CW) or Yellow
and White (CW CY) Codominance
10/20- BIO Warm Up
1.
2.
A colorblind man has children with a woman who is
a carrier for colorblindness. What are the
genotypic and phenotypic ratios of their
offspring?
If a male inherits a sex-linked trait, like
hemophilia, which parent did he inherit it from?
How do you know? Explain.
10/20 - BIO Warm Up
A colorblind man has children with a woman who
is a carrier for colorblindness. What are the
genotypic and phenotypic ratios of their offspring?
XB=normal, Xb=colorblind
1.
1.
2.
¼ XBXb : ¼ XbXb : ¼ XBY : ¼ XbY
¼ female, carrier : ¼ female colorblind : ¼ male
normal vision : ¼ male, colorblind
If a male inherits a sex-linked or X-linked trait, like
hemophilia, which parent did he inherit it from?
How do you know? Explain.
2.
1.
He inherited it from his mother because his father gave
him his Y chromosome and his mother gave him his X
chromosomes. X-linked traits are located on the X
chromosome.
10/21 Bio Warm Up
1.
2.
3.
What is a karyotype and what are they used
for?
What causes chromosomal disorders?
What is Turner’s syndrome? What is Klinefelter’s
syndrome?
10/21 Bio Warm Up
What is a karyotype and what are they used for?
1.
A picture of all of the chromosomes in a cell.
Karyotypes are used to diagnose chromosomal
disorders.
1.
What causes chromosomal disorders?
2.
Nondisjunction – When homologous pairs or sister
chromatids don’t separate correctly during meiosis.
1.
3.
What is Turner’s syndrome? What is Klinefelter’s
syndrome?
1.
2.
Turner’s syndrome: XO
Klinefelter’s syndrome: XXY