2A- Intro to Medical Genetics

Question 1

What are chromosome disorders?

Answer 1

Entire chromosomes or large segments of them are missing, duplicated or altered

Question 2

What are single-gene disorders?

Answer 2

Single genes are altered. Classified as autosomal dominant, autosomal recessive or X-linked.

Question 3

What are multifactorial disorders?

Answer 3

Combination of multiple genetic and environmental causes.

Question 4

What are mitrochrondrial disorders?

Answer 4

Diseases caused by alteration in the small cytoplasmic mitochondrial chromosome

Question 5

What has the trend of the genetic disease diagnosis and treatment been like over the past 50 years?

Answer 5

public health improved and genetic diseases became a larger percentage of genetic deaths among children in developing countries

Question 6

What % of the genome codes functional proteins?

Answer 6

1%

the rest of the genome sits in unemployed hippy circles chanting that they are the 99%

Question 7

What makes up 55% of the genome?

Answer 7

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

repetitive DNA

Question 8

What is dispersive repetitive DNA?

Answer 8

scattered singly throughout the genome. Do not occur in tandem.

Question 9

What are the 2 forms of dispersive repetitive DNA?

Answer 9

Short Interspersed Elements (SINEs) and Long Interspersed Elements (LINEs)

Question 10

How long are SINEs?

Answer 10

90-500bp

Question 11

How long are LINEs?

Answer 11

Can be up to 7000 bp

Question 12

What is satellite DNA?

Answer 12

repeats are clustered together in certain chromosome locations, where they occur in tandem (the beginning of one repeat occurs immediately adjacent to the end of the another)

Question 13

What are α-Satellites?

Answer 13

tandem repeats of a 171-bp sequence that can extend to several million base pairs or longer.

Question 14

Where are α-Satellites found?

Answer 14

Near the centromeres

Question 15

What are minisatellites?

Answer 15

blocks of tandem repeats (each 14 to 500 bp long) whose total length is much smaller, usually a few thousand base pairs. Vary in length among individuals.

Question 16

What are microsatellites?

Answer 16

even smaller (1-13 bp long). Vary in length among individuals.

Question 17

What happens during prophase of mitosis?

Answer 17

chromosomes condense and coil. Sister chromatids attach at centromere. Spindle fibers begin to form from the 2 centrioles on opposite sides of the cell.

Question 18

What occurs during metaphase of mitosis?

Answer 18

chromosomes are at their most highly condensed state. Clinical diagnosis of chromosome disorders is usually based on metaphase chromosomes. Spindle fibers begin to contract and pull the centromeres.

Question 19

What occurs during anaphase of mitosis?

Answer 19

Centromere of each chromosome splits allowing the sister chromatids to separate. Chromatids pulled to opposite sides of the cell

Question 20

What occurs during telophase of mitosis?

Answer 20

new nuclear membranes around 2 sets of 46 chromosomes. Chromosomes begin to decondense. 2 diploid daughter cells formed.

Question 21

What occurs during the replication division stage (meiosis I)?

Answer 21

two haploid cells are formed from a diploid cell. These are oogonia in females and spermatogonia in males.

Question 22

What occurs during the interphase I stage of meiosis I?

Answer 22

replication of chromosomal DNA

Question 23

What occurs during the prophase I stage of meiosis I?

Answer 23

chromatin strands coil and condense

Question 24

What occurs during the synapsis of prophase I?

Answer 24

homologous chromosomes pair up, side by side, lying together in perfect alignment. Does not occur in mitosis

Question 25

What occurs during the bivalent stage of prophase I?

Answer 25

chromatids of the 2 chromosomes intertwine. This is 2 chromosomes in a unit

Question 26

What occurs during the tetrad stage of prophase I?

Answer 26

This is 4 chromatids intertwined in a unit

Question 27

What occurs during the chiasmata stage of prophase I?

Answer 27

Cross-shaped structures that mark attachments between the homologous chromosomes. This indicates a point where the homologous chromosomes exchange genetic material by crossing over.

Question 28

What occurs during metaphase I of meiosis I?

Answer 28

Completion of spindle formation and alignment of bivalents which are still attached at the chiasmata

Question 29

What occurs during anaphase I of meiosis I?

Answer 29

chiasmata disappear and the chromosomes are pulled by the spindle fibers to opposite poles of the cell. Centromeres do not duplicate and divide, so that only half of the original number of chromosomes migrates towards each pole.

Question 30

What occurs during telophase I of meiosis I?

Answer 30

chromosomes reach opposite sides of the cell. 2 haploid daughter cells are formed.

Question 31

Tell me the process of the IPMAT of the equational division stage(meiosis II)

Answer 31

Interphase II – No replication of DNA Prophase II – Spindle fibers begin to form from the 2 centrioles on opposite sides of the cell. Metaphase II – spindle fibers pull the chromosomes into alignment. Anaphase II – chromosomes pulled to opposite sides of the cell. Chromatids are now serparated but chiasma formation and crossing over cause the chromatids to possibly not be identical. Telophase II – New membranes formed around the chromosomes and cytokinesis occurs.

Question 32

What is the end result of meiosis II?

Answer 32

End result is 4 functional gametes in males and 1 functional gamete and 3 polar bodies for females

Question 33

How long does meiosis occur for a man during the course of his life?

Answer 33

All his life

Question 34

What is the process of development from a spermatogonia to a sperm?

Answer 34

Spermatagonia (diploid cells in seminiferous tubules; 46 pairs of chromosomes) --> Primary Spermatocytes (diploid cells produced after several mitotic divisions; 46 pairs of chromosomes) --> Secondary Spermatocytes (primary spermatocytes undergos meiosis I; 23 pairs of chromosomes) --> Spermatids (secondary spermatocytes undergo meiosis II; 23 single stranded chromosomes) --> Spermatids lose most of cytoplasm and develop tails to become mature sperm cells

Question 35

When does female oogenesis stop?

Answer 35

Before birth

Question 36

Give the oocyte development in females

Answer 36

Diploid oogonia divide mitotically to produce primary oocytes by the third month of fetal development. Meiosis I occurs only when a mature primary oocyte is ovulated. In meiosis I, the primary oocyte produces one secondary oocyte (containing the cytoplasm) and one polar body. The secondary oocyte then emerges from the follicle and proceeds down the fallopian tube with the polar body attached to it. Meiosis II begins only if the secondary oocyte is fertilized by a sperm cell. If this occurs, one haploid mature ovum, containing the cytoplasm, and another haploid polar body are produce.

Question 37

When does crossing over occur?

Answer 37

While the chromosomes are close to one another in prophase I, they exchange genetic material. This allows for 4 different daughter cells to be formed.