Week 4 - The biology of the developing nervous system Flashcards
At fertilisation what is the name of the cell that is formed by the fusing of the egg and sperm?
Zygote
What is a zygote?
The single cell created by the fusion of sperm and egg where genetic material from each is combined
What does diploid mean?
A cell that carries two complete paired sets of chromosomes
What term do we use to refer to two complete paired sets of chromosomes?
Diploid
What is the term for reproductive cells?
Gametes
How many sets of chromosomes do gametes have?
One
What is the name given to a cell which only carries one set of unpaired chromosomes?
Haploid
What does haploid mean?
A cell that only has one set of unpaired chromosomes
When the genetic material of a cell is replicated and the cell has divided, what is the name for the two n ew cells that are formed?
Daughter cells
What are daughter cells?
The two new cells which are created as a result of the process of cell division
What is the term for any cell other than reproductive cells?
Somatic cells
What are somatic cells?
All cells other than gametes?
What are the two main phases of the cell cycle?
- Interphase
- Mitotic phase
What is the name for the sequence of events which occurs leading and up to somatic cell division?
Cell cycle
What happens during the interphase part of the cell cycle?
The cell prepares to divide
What happens during the mitotic phase of the cell cycle?
Division occurs
What are the three subphases of interphase called?
- G1
- S
- G2
What happens during the G1 stage of the cell cycle?
The cell becomes highly active and prepares for division by replicating many of its organelles and synthesising proteins
What is the name for the stage of the cell cycle where the cell replicates its DNA so that there are two complete copies available?
The S phase
What happens during the G2 stage of the cell cycle?
Division occurs
What is the name for the final stage of the interphase part of the cell cycle?
G2
What part of the cell cycle occurs after the G2 stage?
The mitotic phase
What are the names of the two processes of the mitotic phase of the cell cycle?
- Mitosis
- Cytokinesis
What is mitosis?
The part of the cell cycle where the nucleus divides
What is cytokinesis?
The part of the cell cycle where the cytoplasm divides
What are the four stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What is the order of the four stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
At the end of the mitotic stage of cell division, the cell has divided and two new cells are formed. What is the name for those new cells?
Daughter cells
After dividing, what two things may the cell do?
It may either re-enter G1 and divide again, or pause
What is the G0 stage of cell division also known as?
The quiescent phase
What happens to the cell during the quiescent phase of the cell cycle?
Nothing, it has paused dividing
Is there a limit to how long a cell may remain in the G0 or quiescent phase of the cell cycle?
No
DNA is replicated in which phase of the cell cycle?
S phase
During the mitotic phase of cell division, what two things occur?
- Mitosis
- Cytokinesis
What happens during the prophase part of mitosis?
Chromatin fibres shorten and condense in order to form chromosomes
What are chromatids?
Two identical copies of a chromosome, joined at the centromere, that are involved in cell division
What is the name for the specialised region on a chromosome which serves as the attachment point for spindle fibres during cell division?
A centromere
What is the name for the protein complex which surrounds the centromere?
The kinetochore
What happens during the prophase stage of mitosis?
The copied DNA condenses into chromosomes, which are made up of two identical sister chromatids
What are sister chromatids?
Two identical copies of a chromosome, joined at the centromere, which are produced during DNA replication and separated during cell division
What is the name for the two identical copies of a chromosome which are produced during DNA replication?
Sister chromatids
During which phase of mitosis does the nuclear envelope begin to break down?
Prophase
What happens to the chromosomes during the metaphase stage?
They line up along the centre of the cell
Why do chromosomes line up along the centre of the cell during the metaphase stage of mitosis?
To ensure that when they split, each daughter cell receives an equal and complete set of genetic information
In the anaphase stage of mitosis, what occurs?
The sister chromatids are pulled apart, towards opposite ends of the cell
How are the sister chromatids pulled apart during the anaphase stage of mitosis?
By spindle fibres that attach to the centromere of each chromatid
What is the name for the stage of mitosis where the nuclear envelope reforms
Telophase
What is a nuclear envelope?
A double membrane that encloses the cell’s nucleus, regulating material flow in and out of the nucleus
What do we call it when a cell physically divides into two separate daughter cells?
Cytokinesis
When a cell divides and two identical copies of the cell are produced, what do we call this?
Symmetrical division
What does the term cytokinesis refer to?
The cell membrane pinching in around the middle of the cell and the cell splitting in to two daughter cells
Which is the most important type of cell division?
Asymmetrical
What is the zygote called when it reaches the 16-cell stage of development at around day 4?
A morula
What is a morula?
The ball of cells that reaches the uterus at around day 3-4 post-fertilisation
What is the name for the ball of cells at the stage that it implants into the wall of the uterus?
A blastocyst
What is a blastocyst?
The ball of cells which implants into the uterine wall
What is it that makes the blastocyst different from a morula?
It has two different types of cells within it
What is the name of the outer layer of the blastocyst?
The zona pellucida
What type of cells make up the outer layer of the blastocyst?
Trophoblast cells
What do trophoblast cells go on to become after the blastocyst implants into the uterus?
The placenta
What is gastrulation?
The formation of three distinct tissue source layers via cell diversification
Which type of cell division is necessary for cell diversification?
Asymmetrical
What do ectoderm cells go on to become?
- Skin
- Hair
- The lining of structures such as the nose and mouth
- The nervous system
What do mesoderm cells go on to become?
- Muscles
- Skeleton
- Blood
What do endoderm cells go on to become?
The lining of the digestive tract, respiratory tract and bladder
What type of cells do each of the three layers formed during gastrulation go on to form?
- Ectoderm cells
- Mesoderm cells
- Endoderm cells
Around roughly how many days post-fertilisation does the nervous system start to develop?
18 days
The development of the nervous system begins shortly after which other process has occurred?
Gastrulation and the generation of the ectoderm layer
The developing nervous system arises from a layer of ectoderm known as the what?
The neural plate