Intro to cell division

Question 1

The developmental process from a single cell to a baby (in 9 months)
is called :

Answer 1

Embryology

It provides a logical framework for understanding adult anatomy
Provides a bridge between basic sciences and clinical sciences.

Question 2

The first ___ weeks of human development is called the embryogenesis and the product is called ___.

Answer 2

8 weeks
Embryo

Question 3

The process of the progressing from a single cell up to the period of establishing organ primordia is called ______.

Answer 3

Embryogenesis

Question 4

Define teratology

Answer 4

The study of embryological origins and causes for birth defects

Question 5

What is the definition of gametogenesis :

Answer 5

Preparation of male and female germ cells for fertilization.

Question 6

Fertilization refers to the fusion between male and female _____.

Answer 6

Pronucleus.

Question 7

The cell that results from the union of an oocyte and sperm during fertilization is called ______.

Answer 7

Zygote

Question 8

Puberty refers to the period during which __________ develop. Usually occurs around ____ years in girls and ____ in boys.

Answer 8

Secondary sexual characteristics
12-15 in females
13-16 in boys

Question 9

Briefly describe the chormosome theory of inheritance.

Answer 9

The idea that genes are located on chromosomes.

It states simply that chromosomes, which are seen in all dividing cells and pass from one generation to the next, are the basis for all genetic inheritance.

Genes that site close to each other on the same chromosome tend to be inherited together : this is the principle of linked genes.

In somatic cells chromosomes appear as 23 homologous pairs to form diploid number of 46.

There are 22 pairs of matching chromosomes (autosomes) and one pair of sex chromosomes.

Each gamete contains an haploid number of 23 chromosomes and the union of gametes at fertilization restores the diploid number.

Question 10

The cell cycle completes in two phases : name them and explain them.

Answer 10

1. Interphase : period in the cell cycle between the end of a previous division and the start of the new division
2. M phase : when the cell can reach a certain size or receives a certain signal, it will start the process of dividing (mitosis or meiosis)

Question 11

Mitosis occurs in both somatic and germ cells. It maintains constant chromosome number and genetic stability in all somatic cells. It increases the cell number so that the zygote transforms into a multicellular adult. It also provides new cells for repair, regeneration and wound healing.

Answer 11

https://www.youtube.com/watch?v=8uzHTKdv_Sw

Question 12

Meiosis occurs only in the sperms and the oocytes. It is responsible for the formation of germ cells (gametes). It reduces the number of chromosomes from 46 to 23 in each germ cell in order for each gamete to have an haploid number of chromosomes.
During meiosis, crossing over occurs which produces a group of new traits in the genetic material of new cells.

Answer 12

https://www.youtube.com/watch?v=kQu6Yfrr6j0

Question 13

Name the phases of interphase :

Answer 13

G1 phase

S phase

G2 phase

** G0 is when the cell cycle arrests

Question 14

Describe G1 phase of interphase

Answer 14

G1 phase : growth in all cellular contents and growth in size of cell but no change in the chromosome (only the cytoplasm changes)

Question 15

Describe S phase of interphase

Answer 15

S phase : Synthesis of new DNA (active synthesis of a new set of all the 46 chromosomes - thus each chromosome will duplicate but stay attach to eachother)

Question 16

Describe G2 phase of interphase

Answer 16

G2 phase : preparation for cell division (marked growth of cellular components in prep for dividing into 2 new cells).

Cells in G2 phase are characterized by :

Intact nuclear envelops

The nucleus contains a nucleoli

Two centrosomes are formed, each with 2 centrioles

Question 17

In the G2 phase, can chromosome be seen individually? why or why not.

Answer 17

No, because they have not condensed.

Question 18

During mitosis, _____ phase is the longest and _____ phase is the shortest.

Answer 18

Metaphase

Anaphase

Question 19

Regarding cytokinesis, the plasma membrane becomes indented to form the _____.Then contraction of the cytoskeleton will lead to formation of two new cells.

Answer 19

Cleavage furrow

Question 20

Meiosis 1 is called _____ division, while meosis 2 is called _____ division.

Answer 20

Reduction

Equatorial

Question 21

What is a chiasmata ?

Answer 21

a point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands.

Question 22

Pairing homologous chromosomes is referred to as _____. Does it occur in meiosis 1 or 2 ?

Answer 22

Synpasis

1

Question 23

In meoisis 1, ______ homologues duplicated chromosomes align at the metaphase plate. In meiosis 2, only ____ homologous duplicated chromosomes align.

Answer 23

46

23

Question 24

In meiosis 1, do centromeres split ?

What about in meosis 2 ?

Answer 24

No, they do not split in meiosis 1

Yes, they do split in meiosis 2

Question 25

The end product of meiosis 1

Answer 25

2 secondary gametocytes

(Haploid)

Question 26

The end product of meiosis 2 is :

Answer 26

4 gametes are formed having half chromosome number

Question 27

Chromosomal abdormalities could be _____ or _______.

Answer 27

Numerical or structural

Question 28

What is aneuploidy as opposed to euploidy

Answer 28

An abnormal number of chromosomes

Euploidy is the normal number of chromosomes (i.e. 46)

Question 29

True or false. Abnormalities in chromosomes number may originate during meiosis (1& 2 ) or mitosis due to non disjunction.

Answer 29

True

https://www.youtube.com/watch?v=sg7xe8C9DmQ

Question 30

When someone has an extra pair chromosome its is called ____. When someone has a pair missing it is referred to as_____.

Answer 30

Trisomy

Monsomy

Question 31

Occasionally, nondisjunctions occurs during mitosis in an embryonic cell during the earliest cell divisions. Such conditions lead to _______. With some cells having an abdnormal number of chromosomes and others being normal. Mosaic Down, Klinefelter, Turner and neurofibromatosis are all examples.

Answer 31

Mosaicism.

Question 32

Give 3 examples of trisomy of autosomes.

Answer 32

trisomy 21 (Down syndrome)

trisomy 18 (Edwards syndrome)

trisomy 13 (Patau syndrome)

Question 33

Give 2 examples of trisomy of sex chromosomes

Answer 33

Klinefelter syndrome 47 (XXY)

Triple X syndrome 47 (XXX) : pts with Triple X syndrome are infantile, with scanty menses and some degree of mental retardation. They have two sex chromatin (Barr) bodies in their cells.

Question 34

Give 1 example of monosomy

Answer 34

Turner syndrome 45 (XO)

Question 35

Structural chromosome abnormalities usually result from chromosome breakage. Breaks are caused by environmental factors such as viruses, radiation and drugs. Two types of structural chromosome abnormalities exist and they are ___ and ___.

Answer 35

Deletions

Translocations

Question 36

Give one example of a syndrome caused by chromosome deletion.

Answer 36

Cri-du-chat

Caused by a partial deletion of the short arm of chromosome 5.

Affected children have a cat-like cry, microencephaly, mental retardation and congenital heart disease.

Question 37

Translocations is when a portion of a chromosome is transferred to another chromosome. 2-3 % of ________ cases are due to translocations between chromosome 14 & 21.

Answer 37

Down syndrome

Question 38

Sometimes, only a few contiguous genes are deleted which is referred to as microdeletions.

microdeletions on the maternal chromosome 15 causes ______.

Answer 38

Angelman syndrome.

Children are mentally retarded, cannot speak, exhibit poor motor development, and are prone to unprovoked and prolonged periods of laugher.

Question 39

Which syndrome does this refer to : microdeletion on the paternal chromosome 15 that causes affected individuals to have hypotonia, obesity, mental retardation, hypogonadism and cryptorchidism (undescended testies)

Answer 39

Prader-Willi syndrome

Question 40

Normally, FMR1 gene makes a protein needed for the brain to grow properly. A defect in this gene makes the body produces too little of the protein or none at all. People affected by this syndrome are mentally retarded, have prominent jaw, large ears and pale blue irises. Boys and girls can both be affected, but since boys only have 1 X chromosome, a single fragile X is likely to affect them more severely.

Answer 40

Fragile X syndrome