EOY B2 Flashcards
How many sections is DNA divided into? What are they called?
46 chromosomes
How many different types of chromosomes are there?
23
What is the 23rd pair of chromosomes?
Sex chromosomes
What are the women and men sex chromosomes?
Women have xx
Men have xy
When do chromosomes look like x’s?
Only before cell division, before undergoing Meiosis or Mitosis
What is a gene?
A section of DNA that codes for a protein. It is like a small section of a chromosome
What is a genome?
The entire set of genetic material in an organism
What can sequencing a genome do?
Help understand inherited disorders and can help the person with it understand what to do to prevent risks and what medication they should take
What is a karyotype?
A picture of all of a person’s chromosomes.
What are homologous chromosomes?
They are from different parents but contain the same types of genes in the same location.
What are autosomal chromosomes?
1-22 They don’t directly determine sex
What is monosomy?
Having one chromosome where you should have a homologous pair
What is Turner’s syndrome?
Where someone has only a single x sex chromosome
What is trisomy 21?
Down’s syndrome- 3 homologous chromosomes in 21.
How many main stages of the cell cycle are there?
3- Growth, DNA replication, Mitosis (Cytokinesis)
What happens in step one of three of the cell cycle?
Cell grows in size
Increases number of sub cellular structures (mitochondria, ribosomes)
DNA replicated to form two copies of each chromosome ready for cell division
When no dividing, DNA is in long strings, when cell prepares for division, DNA condenses into chromosomes.
Then it duplicates each of the 46 chromosomes and the duplicate stays attached to the original chromosome so together they form an x shape
What happens in step two of three of the cell cycle?
Mitosis
When the cell is ready to divide, all the chromosomes line up in the centre of the cell.
Fibres come from each side of the cell and attach to their respective half of each chromosome.
These fibres pull the arms of the chromosome to each side of the cell which are called poles.
Keep Going!!!
🙂↕️🩵🧋
What happens in step three of three?
Cytokinesis-
Cell membrane and cytoplasm pull apart making 2 daughter cells. Both have the same genetic material (so are identical).
What is the difference between the cell cycle and mitosis?
The cell cycle refers to the cell’s lifecycle or the period of cellular growth and DNA replication. Mitosis represents the final step in the cell cycle. Mitosis results in the production of two identical daughter cells.
What is the interphase?
This is when nothing significant happens to the cell, most cells spend more time here.
This is except cancer cells
What is the P in PMAT?
Prophase- Nucleus is still there, chromosomes are condensing (they are visible)
What is M in PMAT?
Metaphase- (middle)
Chromosomes line up middle of the cell, nucleus disassembled
What is A in PMAT?
Anaphase- (away)
Chromosomes go to poles via ‘spindles’
What is T in PMAT?
Telophase
New nuclei forming around both groups of chromosomes.
Then cytokinesis
What happens if a cell is faulty?
It will destroy itself- apoptosis
What is a gene?
A small packet of information that controls a characteristic or part of a characteristic of your body. It is a section of DNA.
Why are more cells made?
Growth
Development
Replacement of worn out or damaged cells
Where at new cells needed the most?
Hair follicles
Skin
Blood
Lining of digestive system
What kind of cells don’t divide? What does this mean?
Red blood cells
Skin cells
Adult stem cells replace dead or damaged cells
But with nerve cells, they can divide and they are not replaced my stem cells.
How are cells differentiated
Camera roll or saved
Where are undifferentiated cells found in plants?
In plants undifferentiated cells are formed at active regions of the stems and roots, known as the meristems. In these areas mitosis takes place almost continuously. The cells then elongate and grow before they finally differentiate
Unlike in humans, plant stem cells can sometimes…
Redifferentiate
Producing identical offspring is known as …
Cloning
How does cloning in plants work?
Identical plants can’t be made using just a leaf tissue. This is because a plant cell can become unspecialised (in the right conditions) and undergo mitosis many times. Each of these undifferentiated cells will produce more cells by mitosis. Given different conditions, these can then differentiate to form tissues such as xylem, phloem, photosynthetic cells and root hair cells needed to form a new plant which will be identical to the parent
Why is it difficult to clone animals?
As most cells differentiate permanently early in embryo development. The cells can’t change back. This means artificial clones can only be made by cloning embryos in some way.
How are embryonic cells formed?
An egg and sperm cell fuse to form a zygote (a single new cell)
That cell divides and becomes a hollow ball of cells (embryo)
The inner cells of this ball are the embryonic stem cells that differentiate to form specialised cells.
Where can you find adult stem cells?
Bone marrow
Who could benefit from stem cells to help heal damaged body parts?
Spinal injuries
Diabetes
Muscular degeneration in eyes (causing blindness)
In the future maybe even organs which can’t be rejected
How can stem cells be used to help plants?
We produce large numbers of rare plants
We can even bring them back from extinction
Produce identical plants for research -scientists can change variables
Agriculture- produce crops with special features eg: disease resistance
Sell more plants
What are some problems with stem cells?
Many embryonic stem cells come from aborted embryos or spare embryos from fertility treatment
Some people feel that as the embryonic can’t give permission using it is a violation of its human rights.
Religious beliefs means that people can’t interfere with the process of human reproduction
More problems with stem cells
Research is expensive and new
Embryonic stem cells divide rapidly causing the fear of cancer if used to treat people
The stem cells may be infected with viruses
They might trigger an immune response on someone if the stem cells aren’t from a related person (adult stems, embryonic may solve this as embryo is not rejected by mothers)
The patient may need to take immunosuppressant drugs to stop rejection.
People think the research is a waste of money
What have stem cells been able to do so far?
They have been found in the blood around the umbilical cord and the amniotic fluid (avoid ethical issues)
Adult stems cells have been grown but they can only do a limited amount of things. They have been used to cure heart disease and grow new organs such as a trachea.
What is therapeutic cloning?
Involves using cells from an adult to produce a cloned early embryo of themselves, this would provide a perfectly matched embryonic stem cells. They could be used for the donor and they wouldn’t be rejected as the cells would have the same genes as the person. This is proving to be very hard however
