M4: Cell division and prenatal development Flashcards
Which interphase period involves replication of DNA??
S
Mitosis
the period of time in which cells undergo division of nuclear material and cytoplasm
What is cytokinesis or mitosis?
In cell division in eukaryotic cells, mitosis occurs when the nucleus divides and “cytokinesis” a physical process of cell division which divides the cytoplasm of a parent cell into two daughter cells.
Cellular division is a process in which our cells replicate itself, make identical copies of itself. Cellular division involves interphrase and mitosis.
Describe mitosis.
What is cytokinesis?
Mitosis is the division of the nuclei or nuclear material of a somatic cell and includes cytokinesis, which is the division of the cytoplasm
cell cycle is the lifecycle of a cell and is divided into two phases
- interphase
- mitosis
is the period of time in which cells carry out basic function and prepare for cell division.
Interphase
What are the basic difference between germ cells and somatic cells
Germ cells are the reproductive (sex) cells of the body. Germ cells are haploid and contain half the full complement of chromosomes (in humans, 23 in total)
Somatic cells are diploid and contain the full complement of chromosomes (in humans 23 pairs of chromosomes or 46 in total)
True or false
The cell cycle of a germ cell includes meiosis instead of mitosis.
True
What is Meiosis?
is a process where a single cell (germ cell) divides twice to produce four cells containing half the original amount of genetic information. These cells are sex cells - sperm in males or eggs in females.
Describe the differences between Sister chromatid vs Non-sister chromatids
Sister chromatid: identical copies of a chromatid having the same genes and alleles whereas in case of non sister chromatid, one strand is inherited from its mother while the other one is inherited from its father.
Non-sister chromatids: pairing of a paternal chromosome and a maternal chromosome (pairing of a homologous chromosome) (pairing of different DNA molecules.
A cell that is capable of dividing alternate between periods of mitosis and nondivision. The phase or period of time between cell division is known as _________. Because mitosis takes less than an hour to complete, the vast majority of cells in the body at any given time are in _______.
______ is the period when DNA is replicating and growth of the cell takes place.
Interphase
What is the characteristic of prophase?
DNA has already been replicated, now chromosomes become visible under the microscope
What is the key characteristic of metaphase?
The chromosome pairs line up at the midline of the cell, attached to the mitotic spindle.
What is the key characteristics of anaphase (3 phase of mitotic division)
Chromosomes separates (they move along the mitotic spindle to opposite poles of the cell
What is the hallmark of telophase in mitosis?
In the final stage of cell division, a new nuclear envelope is formed and the mitotic spindle breaks down. This phase comes before the division of the cytoplasm.
What is a morula?
What prenatal development stage does it occur?
Up to 72 hours after fertilization, cells undergo a series of mitotic division in which a morula is formed.
It is essentially a solid ball of cells resulting from mitotic division of a fertilized ovum (zygote).
A morula is characteristic of stage 2 of prenatal development.
What typically occurs during Stage 4 (around Day 6) of prenatal development?
The fertilized ovum, now known as a blastocyst is implanted onto the inner lining of the uterus, which is faciliated by tropblast cells via enzyme secretion
What is a blastocyst?
What stage of prenatal development does it occur in?
A blastocyst is formed after 4-5 days following fertilization. This is a mast of cells that is formed from two types of cells: embryoblast and trophoblast cells which lines the inner and outter layer respectively.
This is refer to as stage 3 of prenatal development
What occurs during stage 5 of prenatal development ?
About two weeks following fertilization, the blastocyte is now an embryo which is implanted into the endometrium.
What is the marker of Stage 6 (day 13-15) of prenatal development
The formation of a primitive streak which is a linear group of cells that forms in the embryo and establishes the cranial-caudal axis
Stage 7 of prenatal development
Describe the 3 distinct cell layers (process of gastrulation)
Formation of three distinct cell layer
ectoderm: skin & nervous system
mesoderm: heart, muscles, bones, kidneys
endoderm: respiratory sys, livers, pancreas, GI, thryoid
What occurs during stage 8 (18 days) of prenatal development?
the formation of the neural tube which would lead to the formation of the spinal cord and brain later on.
Characteristics of Stage 9 of prenatal development
Formation of somites - mesodermal cell grouped together to form the vertebrae and muscles
Stage 10 (22-23 days) of prenatal development
the heart tube forms & cardiac muscle contraction begins. Both eye and ear cells are present.
Stage 11 of prenatal development (more than 3 weeks)
heart tube begins beating
Stage 12 of prenatal development (1 month)
- neural tube closure,
- budding of upper and lower limbs and valves of the heart,
- differentiation of liver, stomach, pancreas, and lung cells
What is the difference between prometaphase and telophase?
(nuclear envelope and mitotic spindles)
In prometaphase, the nuclear envelop breaks down and the mitotic spindle starts to develop between the centrioles.
In Telophase, the nuclear envelop redevelops and the mitotic spindle breaks down
What are the phases in meiosis ?
What are the two factors in meiosis that contribute to the genetic diversity of sexual reproduction?
1) the creation of tetrads, where homologous pairs of nonsister chromatids swap pieces of chromosome in prophase 1 - this “crossing over” of genetic information allows for genetic diversity because after crossing over, the chromosomes now contains new combination of genetic material.
2. Random assortment occurs which means sister chromatids separates in such a way that it allows for new chromosome combinations to be made during anaphase 1.
What is the difference between meiosis 1 and 2?
In meiosis one, a diploid cell germ cell, mixed with paternal and materal information, divides into two diploid daughter cells. Each diploid cell contains a full set of genetic information
In meiosis two, the diploid daughter cells forms 4 haploid daughter cells. (egg, sperms). Only half a set of genetic information is distributed to each daughter cel.
What are male and female reproductive cells called?
Spermatozoa and ovum
What is a function of the trophoblast cells
secrete protein digesting enzymes to break down the endometrium to create space for the developing blastocyte
What occurs during week 12-16 of fetal period?
3-4 months
- the fetus moves
- reflexes are present
- heart beat detected in an ultrasound,
- body hair
- distinguishable fetal sex
- fetus begins swallowing amniotic fluid and forming both urine in the kidneys and meconium in thee intestines.
What is the earliest that the fetus may be able to survive a premature birth.
Week 26
Apoptosis is programmed cell death.
T or F
It is regulated by intracellular and intercellular chemical messengers
TRue
