Lecture 3 - About, The Central Points, 3.1 Chromosomes (Pg: 1 to 21)

Question 1

About:

1. That each human cell normally has _____ pairs of chromosomes
2. One of each pair comes from the ____ and the other from the ____
3. The process where the genome of the cell is divided is called meiosis and it is a ____ ____
4. Meiosis occurs continuously in male _____ to produce new sperm.
5. Meiosis occurs _______ in female gonads to produce eggs.
6. Sperm fertilize an egg to make a _____ zygote that divides mitotically to produce a baby.
7. Because there are two chromosomes, there are ____ copies of each gene in a normal cell (somatic cell)
8. Sometimes errors occur in meiosis (rarely) resulting in sperm or eggs with abnormal numbers of chromosomes resulting from faulty cell division or ____________
9. The effect of non-disjunction varies depending on the _______ involved.

Answer 1

1. 23 pairs of chromosomes
2. one of each pair comes from the egg and the other from the sperm
3. The process where the genome of the cell is divided is called meiosis and it is a reduction division
4. Meiosis occurs continuously in male gonads to produce new sperm
5. Meiosis occurs discontinuously in female gonads to produce eggs.
6. Sperm fertilize an egg to make a diploid zygote that divides mitotically to produce a baby.
7. Because there are two chromosomes there are two copies of each gene in a normal cell (somatic
   cell).
8. Sometimes errors occur in meiosis (rarely) resulting in sperm or eggs with abnormal numbers of chromosomes resulting from faulty cell division or non-disjunction.
9. Chromosome

Question 2

The Central Points

1. Most humans have 46 chromosomes (23 pairs) but chromosome numbers can vary
2. Possible to test fetal chromosome number
3. Changes in chromosome number or structure can cause _______
4. Problems with genetic testing can result in lawsuits

Answer 2

3. genetic disorders

Question 3

Case A: Results Worry Pregnant Woman

Answer 3

• Martha, age 41, is 18-weeks pregnant
• Age increased risk of chromosomal abnormalities
• Amniocentesis recommended
• Test results:
  o No Down syndrome
  o Fetus is XYY (Jacobs syndrome)

Question 4

3.1 Chromosomes

1. Homologous pairs of chromosomes carry _______ genes
2. ______ are different forms of the same gene

3.
a) 46 is the human diploid (____) chromosome
o XX or XY
b) o 22 pairs of ______ (1-22)

Answer 4

1. identical
2. alleles
3. a) 2N (means 46 chromosomes)
   b) autosomes (1-22)

Question 5

3.1 Chromosomes

1) Eggs and sperm are produced by _____

2) Begin with 2 copies of each chromosome (46) (diploid)

3) Two divisions _____ __ and _______ _______

4) Homologous chromosome pairs ______

5) Produces ______ cells with 1 copy of each chromosome (23)

Answer 5

1) * Eggs and sperm are produced by meiosis

2) * Begin with 2 copies of each chromosome (46) (diploid)

3) * Two divisions meiosis I and meiosis II

4) * Homologous chromosome pairs separate

5) * Produces haploid cells with 1 copy of each chromosome (23)

Question 6

Chromosome Parts

1. Centromere
   a) p arm (_____ arm)
   b) ____ arm (long arm)
2. Telomeres
   a) _____ with each cell division
   b) Telomers was founded by _______ _______ and
   Jack Szostak
   b) Telomereas were founded by ______ _________ & Liz Blackburn
   c) All three got a Nobel prize in 2009
3. Note: Each _________ is a double-stranded DNA identical to its sister.

Answer 6

1 Centromere
a) p arm: the short arm
b) q arm: the long arm

2. Teloemers
   a) shorten with each cell division
   b) telomeres were founded by Liz Blackburn and Jack Szostak
3. Each sister chromatid is a double-stranded DNA that is an identical copy of its sister.

Question 7

Comparison Between Homologs and Sister Chromatids

1. Centromere:
   a) homologous chromosomes: D______
   b) size: S____
   c) Genes: same
   d) alleles: same or _______
2. Sister Chromatids
   a) homologous chromosomes: S______
   b) size: S____
   c) Genes: same
   d) alleles: _____

Answer 7

1. Centromere:
   a) homologous chromosomes: Different
   b) size: Same
   c) Genes: same
   d) alleles: same or different
2. Sister Chromatids
   a) homologous chromosomes: Same
   b) size: Same
   c) Genes: same
   d) alleles: same

Question 8

2.6 Cell Division by Meiosis: The Basics of Sex

1. Meiosis

a) Produces ____ haploid cells containing only one copy (paternal or maternal) of each chromosome (23)

b) Two Rounds of Meiotic Division:
▪ Meiosis I:

• Reduces the chromosome number from ____ to _____
• ________ results in genetic variation

▪ Meiosis II:

• Separates the ______ _________
• ____ haploid cells result

Answer 8

1.
a) Meiosis produces four haploid cells containing only one copy (paternal or maternal) of each chromosome (23)

b)
▪ Meiosis I
- Reduces the chromosome number from diploid to haploid
- Crossing over results in genetic variation

▪ Meiosis II
– Separates the sister chromatids
- Four haploid cells result

Question 9

The Behaviour of chromosomes in mitosis and meiosis

Answer 9

see figure from martini anatomy and physiology

Question 10

Meiosis to form sperm and egg cells

1) Meiosis is a cell division that gives rise to either a) ____ or b) ____.

2) Meiosis gives rise to a) ____ cells (haploid) with only b) _____ copy of each chromosome.

3) In meiosis I, the homologous chromosomes a) ____ tightly together and b) ______ _______ of the homologous chromosome occur.

This process occurs only in c) ____ and never in mitosis.

Answer 10

1) Meiosis is a cell division that gives rise to either a) sperm or b) an egg.

2) Meiosis gives rise to a) 4 cells (haploid) with only b) one copy of each chromosome.

3) In meiosis I, the homologous chromosomes a) align tightly together and b) crossing over of the homologous chromosome occur.

This process occurs only in c) ____ and never in mitosis.

Question 11

Stages of Meiosis I

1. Meiosis I
   – a) ______ chromosomes separate in
   meiosis.

–Prophase I
a) before the cells begin meiosis, the chromosomes ______.

b) As meiosis begins, chromosomes ____ and shorten, becoming visible in the microscope.

c) Each chromosome is in a diploid (2N) has a ____ partner

d) _________ (synapsis) takes place.

– Metaphase I
a) the chromosome pairs line up along the ____ of the cell.

b) ____ ______ attach to the centromere of each pair

– Anaphase I
a) Members of each homologous pair ______ and move towards b) _____ ______ of the cell.

– Telophase I
a) The chromosomes reach opposite poles of the cell, and the ____ begins to re-form.

b) the ______ divides and two cells are formed.

c) These cells have ____ the number of chromosomes of the original cells and are called haploid cells

–Cytokinesis
a) Cytoplasm divides, forming ____ cells.

Answer 11

1. Meiosis I
   – a) homologous chromosomes separate in
   meiosis.

–Prophase I
a) before the cells begin meiosis, the chromosomes a) duplicate.

b) As meiosis begins, chromosomes b) shorten and become visible in the microscope.

c) Each chromosome is in a diploid (2N) and has a c) matching partner

d) Recombination (synapsis) takes place.

– Metaphase I
a) the chromosome pairs line up along the a) middle of the cell.

b) spindle fibres attach to the centromere of each pair

– Anaphase I
a) Members of each homologous pair a) separate and move towards b) opposite poles of the cell.

– Telophase I
a) The chromosomes reach opposite poles of the cell, and the a) nuclei begin to re-form.

b) the b) cytoplasm divides and two cells are formed.

c) These cells have c) half the number of chromosomes of the original cells and are called haploid cells

–Cytokinesis
a) Cytoplasm divides, forming ____ cells.

Question 12

Stages of Meiosis II:

2. Meiosis II
   – a) ____ ______ separate in meiosis II

–Prophase II
a) ___ ____ formed during meiosis 1. In prophase II, the chromosomes of these cells b) ____ and move toward the c) _____ of the cell.

–Metaphase II
a) the 23 chromosomes in each cell attach to the ______ ______ at their centromere.

b) _____ chromosomes become aligned
at the equator of the cell.

– Anaphase II
a) Each centromere _____ and the newly formed chromosomes (also called ____ _____) move to the b) _______ _______ of the cell.

**newly formed chromosomes: Daughter chromosomes

– Telophase II
a) finally, the chromosomes ______ and the b) ____ _____ reforms.

b) After the cytoplasm divides, the result is ____ cells, each with the _____ number of chromosomes.

c) meiosis is now complete. These cells will undergo further changes and become ______.

–Cytokinesis
a) The cytoplasm divides, forming ___ new
daughter cells

Answer 12

2. Meiosis II
   – a) sister chromatids separate in meiosis II

–Prophase II
a) two cells formed during meiosis 1. In prophase II, the chromosomes of these cells b) recoil and move toward the c) center of the cell.

d) Recomb (synapsis) takes place.

–Metaphase II
a) the 23 chromosomes in each cell attach to the spindle fibres at their centromere.

b) Unpaired chromosomes become aligned
at the equator of the cell.

– Anaphase II
a) Each centromere divides and the newly formed chromosomes (also called sister chromatids) move to the b) opposite ends of the cell.

**newly formed chromosomes: Daughter chromosomes

– Telophase II
a) finally, the chromosomes uncoil and b) the nuclear membrane reforms.

b) After the cytoplasm divides, the result is 4 cells, each with a haploid number of chromosomes.

c) meiosis is now complete. These cells will undergo further changes and become gametes

–Cytokinesis
a) The cytoplasm divides, forming 4 new
daughter cells.

Question 13

Summary of Chromosome Movement during Meiosis (Meiosis I and Meiosis II)

1. There are two chromosomes each with two pairs of sister chromatids.
2. Each chromosome pairs with its ______. What does this mean? The 4 ends of each chromosome pairs with the 4 ends of its homologue chromosome.
3. Paired homologues _____ in Meiosis I. Crossing over takes place between ____ _____ chromatids.
4. Sister Chromatids separate and become ____ chromosomes in meiosis II.

Answer 13

1. There are two chromosomes each with two pairs of sister chromatids.
2. Each chromosome pairs with its homologue.

– What does this mean?
The 4 ends of one chromosome (2 bottom ends and 2 top ends of each sister chromatid) pair with the 4 ends of its homologue chromosome.

3. Paired homologues separate in meiosis 1. Crossing over takes place between non- sister chromatids.
4. Sister Chromatids separate and become individual chromosomes in meiosis 11

Question 14

2.6 Random Assortment and Crossing Over

a) Random assortment of chromosomes in
meiosis (see image)

b) (see the corresponding image)
– In Prophase I (meiosis 1), homologous chromosomes ____ pair with one another

– Crossing overtakes place between ______ chromatids.

– There is a physical exchange of chromosome segments and the _______ they carry.

—- Crossing over generates new combinations of Mom’s and Dad’s _____

Answer 14

a) Random assortment of chromosomes in
meiosis (see image)

b) (see the corresponding image)
– In Prophase I (meiosis 1), homologous chromosomes physically pair with one another

– Crossing overtakes place between non-sister chromatids.

– There is a physical exchange of chromosome segments and the genes they carry.

– Crossing over generates new combinations of Mom’s and Dad’s alleles

Question 15

2.7 Comparison of Sperm and Egg Production in Humans

o Sperm and egg development differ in _____ and ____ of haploid daughter cell

a) Sperm
– Continually produced from _____ until death
— Four mature sperm from one _____

b) Oocytes
– ____ number of primary oocytes arrested in meiosis I produced during _____ _______.

– Meiosis II completed upon ______

– Only ____ mature ovum results from one _____ oocyte

Answer 15

o Sperm and egg development differ in timing and functionality of haploid daughter cell

a) Sperm
– Continually produced from puberty until death
— Four mature sperm from one spermatocyte

b) Oocytes
– a finite number of primary oocytes arrested in meiosis I produced during embryonic development

– Meiosis II is completed upon fertilization.

– Only one mature ovum results from one primary oocyte

Question 16

Formation of Sperm

o Meiosis results in two kinds of haploid, sexual _____; egg and sperm

o Sperm
– Produced by males through _______ within the seminiferous ____ of testes

– Mitotic spermatogonia produce _________

– Meiosis in spermatocytes produces haploid ________ that mature into sperm cells

— Continually produced from puberty until ____

Answer 16

o Meiosis results in two kinds of haploid, sexual gametes; egg and sperm

o Sperm
– Produced by males through spermatogenesis within the seminiferous tubules of testes

– Mitotic spermatogonia produce spermatocytes

– Meiosis in spermatocytes produces haploid spermatids that mature into sperm cells

— Continually produced from puberty until death

Question 17

Maleness and human sperm development

– Maleness is determined by the presence of a ___ chromosome.

• The Y chromosome has a gene for ___ (TDF) that sets up a cascade of _____ in utero
  that causes the regression of female organs and the development of male structures.
• It takes about ___ days for a sperm to develop from the first division of the sperm mother cell
  to the final sperm in the _____ tubules in the testes.
• Sperm counts can be from 0 to ____ million per ml.
• When the number drops to 15 to 20 million sperm per ml, there can be problems with
  _____.

Answer 17

– Maleness is determined by the presence of a Y chromosome.

• The Y chromosome has a gene for SRY (TDF) that sets up a cascade of testosterone in utero
  that causes the regression of female organs and the development of male structures.
• It takes about 72 days for a sperm to develop from the first division of the sperm mother cell
  to the final sperm in the seminiferous tubules in the testes.
• Sperm counts can be from 0 to 300 million per ml.
• When the number drops to 15 to 20 million sperm per ml, there can be problems with
  fertility.

Question 18

Sperm Formation (see image)

1. _________ are the cells that give rise to
   sperm cells.

a) The spermatogonia divide by
_____.

b) One daughter cell remains a
_____that can divide again by
mitosis. The other daughter cell becomes a
primary _______.

2. The primary spermatocyte divides by ____ to form secondary spermatocytes.
3. The secondary spermatocytes divide by meiosis to form _______.
4. The spermatids differentiate to form _____
5. Sustentacular cells, in which the ________ and developing sperm cells are embedded, maintain the blood-testis barrier.

Answer 18

1. Spermatogonia are the cells that give rise to
   sperm cells.

a) The spermatogonia divide by
mitosis.

b) One daughter cell remains a Spermatogonium that can divide again by
mitosis. The other daughter cell becomes a
primary spermatocyte.

2. The primary spermatocyte divides by meiosis to form secondary spermatocytes.
3. The secondary spermatocytes divide by meiosis to form spermatids
4. The spermatids differentiate to form sperm cells
5. Sustentacular cells, in which the spermatogonia and developing sperm cells are embedded, maintain the blood-testis barrier.

Question 19

Formation of Oocytes (see images attached)

1. Oocyte

a) Produced by females through _____ in the ovary.

b) _____ oogonia produce primary oocytes

c) Meiosis in primary oocytes produce ____ (ovum = singular)

Answer 19

1. Oocyte

a) Produced by females through oogenesis in the ovary.

b) Mitotic oogonia produce primary oocytes

c) Meiosis in primary oocytes produce ava (ovum = singular)

Question 20

Maturation and fertilization of the oocyte

1. Oogonia are the cells from which oocytes ___.

a) The oogonia divide by ____ to produce other oogonia and ___ oocytes.

2. Primary oocytes may be produced by the ____ month of prenatal life.

a) Primary oocytes begin the first meiotic division but stop at _____ I.

b) All of the primary oocytes remain in
this state until ____.

3. The first meiotic division is completed in a single mature ____ just before ovulation during each menstrual cycle.

a) A _____ oocyte and the ____ polar body result from the unequal division of the cytoplasm.

4. The secondary oocyte begins the second meiotic division but stops at _____ II
5. The second meiotic division is completed after ______after a sperm cell unites with the secondary oocyte.

a) A secondary oocyte and a second ____ body are formed.

6. Fertilization is completed after the ____ of the secondary oocyte and the sperm cell unite.

a) The resulting cell is called a _____

Answer 20

1. Oogonia are the cells from which oocytes arise.

a) The oogonia divide by mitosis to produce other oogonia and primary oocytes.

2. Primary oocytes may be produced by the fourth month of prenatal life.

a) Primary oocytes begin the first meiotic division but stop at prophase I.

b) All of the primary oocytes remain in
this state until puberty.

3. The first meiotic division is completed in a single mature follicle just before ovulation during each menstrual cycle.

a) A secondary oocyte and the first polar body result from the unequal division of the cytoplasm.

4. The secondary oocyte begins the second meiotic division but stops at metaphase II
5. The second meiotic division is completed after fertilization after a sperm cell unites with the secondary oocyte.

a) A secondary oocyte and a second polar body are formed.

6. Fertilization is completed after the nuclei of the secondary oocyte and the sperm cell unite.

a) The resulting cell is called a zygote

Question 21

Human ovum development

During fetal life, there are about 6 million to 7 million oocytes in the female ovaries, no new
oocytes are produced.

• At birth, there are approximately 1 million oocytes that are arrested in prophase on meiosis I; and by the time of puberty, only about 300,000 remain.
• Of these, only 300 to 400 will be ovulated, usually once per month, during a woman’s
  reproductive lifetime

a) The ovum chosen progresses from _____ I to metaphase II with the production of a ____
body.

b) The ovum that is produced at ovulation is a ______ oocyte arrested in metaphase II.

c) Meiosis II is completed ______ fertilization and a _____ ______ is present in the zygote

Answer 21

a) The ovum chosen progresses from prophase I to metaphase II with the production of a polar
body.

b) The ovum that is produced at ovulation is a secondary oocyte arrested in metaphase II.

c) Meiosis II is completed AFTER fertilization and a polar body is present in the zygote

Question 22

2.7 Sperm Development in Humans (see attached image)

• Sperm Development Overview (a)

1. primary spermatocyte:
   a) Meiosis ___
   b) the number of chromosomes: n or 2n?
   c) how many daughter cells:
2. Secondary spermatocyte:
   a) Meiosis ___
   b) the number of chromosomes: n or 2n?
   c) how many daughter cells:
3. bodies
   a) how many bodies?
   b) the number of chromosomes: n or 2n?
4. Spermatids
   a) how many:
5. Sperm

Answer 22

• Sperm Development Overview (a)

1. primary spermatocyte:
   a) Meiosis I
   b) the number of chromosomes: 2n
   c) how many daughter cells: 1
2. Secondary spermatocyte:
   a) Meiosis I
   b) the number of chromosomes: n
   c) how many daughter cells: 2
3. bodies
   a) how many bodies: 4
   b) the number of chromosomes: 4 bodies with n chromosomes
4. Spermatids
   a) how many: 4
5. Sperm

Question 23

2.7. Egg Development in Humans (see attached image)

1. primary oocyte:
   a) Meiosis:
   b) the number of chromosomes: n or 2n?
   c) how many daughter cells:
2. Secondary oocyte:
   a) Meiosis
   b) the number of chromosomes: n or 2n?
   c) how many daughter cells:
3. First polar body
   a) When does it form?
4. 2- 4 polar bodies
   a) When does it form?
5. Egg
   a) What happens to the 3 other polar bodies?

Answer 23

• Egg Development overview (b)

1. primary oocyte:
   a) Meiosis: I
   b) the number of chromosomes: 2n?
   c) how many daughter cells: 1
2. Secondary oocyte:
   a) Meiosis: I
   b) the number of chromosomes: n
   c) how many daughter cells: 1
3. First polar body
   a) When does it form?
   It forms during meiosis I, where the secondary oocyte is also forming
4. 2- 4 polar bodies
   a) When does it form?
   During meiosis II, the first polar body is formed with the secondary oocyte in meiosis I.
5. Egg
   a) What happens to the 3 other polar bodies?
   They disintegrate, die, get discarded or are absorbed back into the cell, leaving 1 final egg at the end.

Question 24

Table 2.6: Comparing Spermatogenesis and Oogenesis

Spermatogenesis
a) begins at _____

b) The following is the correct order of events in Spermatogenesis (True or false):

1. Spermatogonium (16 days),
2. Primary Spermatocyte (16 days),
3. Secondary Spermatocyte (16 days),
4. Spermatid (16 days),
5. Mature Sperm Total time (64 days)

Oogenesis
a) begins during _______

b) The following is the correct order of events in Oogenesis (True or false):

1. Oogonium: Forms 2-3 months after conception
2. Primary Oocyte: Forms at 2-3 months of gestation. Remains in meiosis I until ovulation, 12-50 yrs after formation.
3. Ootid: Less than 1 day, when fertilization occurs.
4. Mature egg-zygote total time: 12 - 50 years

Answer 24

Spermatogenesis
a) begins at puberty

b) The following is the correct order of events in Spermatogenesis: True

Oogenesis
a) begins during embryogenesis

b) The following is the correct order of events in Oogenesis: True

Question 25

Fertilization

a) The _____ sperm fertilizes the haploid egg in the Fallopian tube and the surface hardens to
form the ____ ______.

b) The diploid zygote undergoes mitotic cleavage several times to form a _____, then a fluid-filled blastocyst.

c) The embryo travels down into the _____ while continuing to divide mitotically.

d) The embryo _____ from the zona pellucida on day 6 and the embryo can implant in the
uterus where it undergoes reorganization called _____ to form the inner cell mass (ICM).

e) ICM is made of three _____ layers (becomes the embryo proper) surrounded by the
trophoblast (becomes the _______).

f) The fetus is usually born __ weeks after the date of the first day of the last menstruation.

• NOTE: On 25 July 1978 the first test tube baby, Louise Brown was born

Answer 25

a) The haploid sperm fertilizes the haploid egg in the Fallopian tube and the surface hardens to
form the zona pellucida.

b) The diploid zygote undergoes mitotic cleavage several times to form a morula, then a fluid-filled blastocyst.

c) The embryo travels down into the uterus while continuing to divide mitotically.

d) The embryo hatches from the zona pellucida on day 6 and the embryo can implant in the
uterus where it undergoes reorganization called gastrulation to form the inner cell mass (ICM).

e) ICM is made of three germ layers (becomes the embryo proper) surrounded by the
trophoblast (becomes the placenta).

f) The fetus is usually born 40 weeks after the date of the first day of the last menstruation.

• NOTE: On 25 July 1978 the first test tube baby, Louise Brown was born

Question 26

Nondisjunction

• Chromosomes ____ to separate meaning that the resulting cells may have too many or __ ___ chromosomes
• Nondisjunction: Gametes and zygotes with a
  an _______ number of chromosomes.
• Aneuploidy is variations in ______ ______ that involves
  one or more chromosomes
  – Most aneuploidies occur from errors in _______
• Figure 3.4: Nondisjunction
  – The failure of chromosomes to _____ ______ at either the first or the second division in meiosis is called ________.

– The result is an ______ number of chromosomes in _____or eggs.

– If these abnormal gametes are involved in _________, the result can be a child with an abnormal number
of chromosomes.

Answer 26

• Chromosomes fail to separate, meaning that the resulting cells may have too many or too few chromosomes
• Nondisjunction: Gametes and zygotes with a
  an abnormal number of chromosomes.
• Aneuploidy is variations in chromosome number that involve one or more chromosomes
  – Most aneuploidies occur from errors in meiosis
• Figure 3.4: Nondisjunction
  – The failure of chromosomes to properly separate at either the first or the second division in meiosis is called non-disjunction.

– The result is an abnormal number of chromosomes in sperm or eggs.

– If these abnormal gametes are involved in fertilization, the result can be a child with an abnormal number
of chromosomes.

Question 27

Other Types of Chromosomal Variations

Answer 27

• Polyploidy
• Euploid
• Trisomy
• Monosomy
• Structural changes
• Aneuploidy

Question 28

Other Types of Chromosomal Variations - Polypoidy

Polyploidy: ___ of chromosomes

Answer 28

Polyploidy: multiple sets of chromosomes

Question 29

Other Types of Chromosomal Variations - Euploid

Euploid: ____ two copies of each chromosome

Answer 29

Euploid: normal two copies of each chromosome

Question 30

Other Types of Chromosomal Variations - Trisomy

Trisomy: _____ copies of one chromosome

Answer 30

Trisomy: 3 copies of one chromosome

Question 31

Other Types of Chromosomal Variations - Monosomy

Monosomy: only ____ copy of a chromosome

Answer 31

Monosomy: only one copy of a chromosome

Question 32

Other Types of Chromosomal Variations - Structural Changes

Structural Changes : duplication, ______, inversion, ____ translocation

Answer 32

Structural Changes : duplication, ______, inversion, ____ translocation

Question 33

Aneuploidy - One type of chromosomal variation

• Effects vary by chromosomal _______
• Many causes of early ________.
• Leading cause of _______ _______ recognized at birth.
• In humans, most aneuploidies are not _______, so the fetus is ______

Answer 33

• Effects vary by chromosomal condition
• Many causes of early miscarriages
• Leading cause of intellectual disabilities recognized at birth.
• In humans, most aneuploidies are not tolerated, so the fetus is miscarried

Question 34

3.3 ID of Chromosomal Abnormalities

• Two tests that give “definitive” results:

o A_______ (> 16 weeks)
- Collects a_______ fluid – ____ ______ grown, and karyotype produced

o Chorionic villus sampling (CVS) ( ____ weeks)
– Rapidly dividing cells that are not grown
– Karyotype within a few days

Answer 34

• Two tests that give “definitive” results:

o Amniocentesis (> 16 weeks)
- Collects amniotic fluid – Fetal Cells grown, and karyotype produced

o Chorionic villus sampling (CVS) (10 to 12 weeks)
– Rapidly dividing cells that are not grown
– Karyotype within a few days

Question 35

Amniocentesis

• Mother over ___ by the pregnancy due date
• ______-trimester amniocentesis carries a slight risk of miscarriage - The Mayo Clinic
• An amniocentesis may be used for _______ and ____ testing in the second trimester of
  pregnancy in the presence of one or more of these
  conditions:

o ____ ____ or previous child with a genetic
disease or chromosomal or metabolic disorder

o Risk of o_______ n______ t____ d_______ (ONTDs), such as spina bifida

o Abnormal maternal screening tests, such as
m______ s_____ a_____-f____ level (MSAFP)

o Risk of a ______-_____ genetic disease

Answer 35

• Mother over 40 by the pregnancy due date
• second -trimester amniocentesis carries a slight risk of miscarriage - The Mayo Clinic
• An amniocentesis may be used for genetic and chromosome testing in the second trimester of
  pregnancy in the presence of one or more of these
  conditions:

o Family History or previous child with a genetic
disease or chromosomal or metabolic disorder

o Risk of open neural tube defects (ONTDs), such as spina bifida

o Abnormal maternal screening tests, such as
maternal serum alpha-fetoprotein level (MSAFP)

o Risk of a sex-lined genetic disease

Question 36

Amniocentesis continued (see image attached)

1. In amniocentesis, a syringe needle, guided by a) ______ is inserted into the uterus.
2. The needle passes through the a)___ ________ to collect a small sample of amniotic fluid that contains cells.
3. The cells can be collected and grown in the laboratory for a) ____ ______.

Answer 36

1. In amniocentesis, a syringe needle, guided by a) ultrasound is inserted into the uterus.
2. The needle passes through the a) fetal membrane to collect a small sample of amniotic fluid that contains cells.
3. The cells can be collected and grown in the laboratory for a) chromosome analysis.

Question 37

Figure 3.8: Chorionic Villus Sampling (see image attached)

1. a) In CVS, a ____ is inserted into the uterus through the b) ____ is used to collect cells from the chorion, a c) ______ is produced by the fetus.
2. a) Cells from the ____ are used for chromosome analysis and ____ preparation.

Answer 37

1. a) In CVS, a catheter is inserted into the uterus through the b) vagina is used to collect cells from the chorion, a
   c) membrane is produced by the fetus.
2. a) Cells from the chorion are used for chromosome analysis and karyotype preparation.

Question 38

Less Invasive Testing Methods

1. Fetal Cell testing from a)______ blood
2. Free fetal DNA (ffDNA)
   – e.g. a) “_______” test can be administered at 10 weeks
3. Improved methods for the analysis of a)_____ - _____ DNA are becoming available
4. Figure 3.9: Amniotic Fluid Contains DNA from
   the a) ___.

– Fetal DNA can cross the b) ____ and
enter the mother’s bloodstream, which contains
DNA from the mother.

– Isolation and analysis of fetal DNA in the maternal blood is an alternative to amniocentesis and ___ ____ ____

Answer 38

1. Fetal Cell testing from a) maternal blood
2. Free fetal DNA (ffDNA)
   – e.g. a) “Harmony” test can be administered at 10 weeks
3. Improved methods for the analysis of a) cell-free DNA are becoming available
4. Figure 3.9: Amniotic Fluid Contains DNA from
   the a) Fetus.

– Fetal DNA can cross the b) placenta and
enter the mother’s bloodstream, which contains
DNA from the mother.

– Isolation and analysis of fetal DNA in the maternal blood is an alternative to amniocentesis and chorionic villus sampling

Question 39

Figure 29.1 Preparing a karyotype (See attached image)

1. a)___________ are made from cells undergoing the b)______ of mitosis

Answer 39

1.
a) Karyotype
b) prophase of mitosis

Question 40

Leading Risk Factor For Trisonomy

Examples of trisomy:

a) Trisomy 13: _____ Syndrome (47,+13)

b) Trisomy ____: Edwards Syndrome (47,+18)

c) Trisomy 21: ______ _______ (47,+21)
- Occurs in 1/800 live births in the US and trisomies are
detected in over ____ % of Downs Syndrome patients.)

Answer 40

a) Trisomy 13: Patau Syndrome (47,+13)

b) Trisomy 18: Edwards Syndrome (47,+18)

c) Trisomy 21: down syndrome (47,+21)

Question 41

Mothers’ chance of having a child with down syndrome per age

Answer 41

Age: Chances of having a child with down syndrome
20 1 in 1,600
25 1 in 1,300
30 1 in 1,000
35 1 in 365
40 1 in 90
45 1 in 30

Question 42

Risks of having a child with down syndrome

1. The risk of causing a a)_______ via amniocentesis can be up to 1/300 to 1/500 if done.
2. After 15 weeks according to the Mayo clinic, the risk is quite small unless the procedure is done prior to a)__ weeks).
3. According to the American Pregnancy Association, it is about a) ______ when done regularly in the clinic concerned.
4. a) ____ carries a risk of causing a miscarriage of up to about 1/100.

• Note. These numbers are dropping all the time as more expertise improves

Answer 42

1. a) The risk of causing a miscarriage via amniocentesis can be up to 1/300 to 1/500 if done.
2. a) After 15 weeks according to the Mayo Clinic, the risk is quite small unless the procedure is done prior to 15 weeks).
3. a) According to the American Pregnancy Association, it is about a) 1/400 when done regularly in the clinic concerned.
4. a) CVS (Chorionic Villus Sampling) carries a risk of causing a miscarriage of up to about 1/100.

• Note. These numbers are dropping all the time as more expertise improves

Question 43

3.4 Effects of Changes in Chromosomes

1) Vary by chromosome and a) ___ of ____

2) Can cause birth defects or a) ___ _____.

3) a) _____ of any autosome is fatal

4) Only a few a)_____ result in live births

Answer 43

1) Vary by chromosome and a) type of variation

2) Can cause birth defects or a) fetal death.

3) a) Monosomy of any autosome is fatal

4) Only a few a) trisomy result in live births