B2 5 Mitosis And Meiosis Flashcards Preview

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Flashcards in B2 5 Mitosis And Meiosis Deck (27)
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What is mitosis?

Mitosis is normal body cell division


Why does mitosis happen?

Mitosis happens in order to produce more identical cells for growth, repair and replacement


Describe the stages of mitosis

The normal body cell copies the genetic information producing four pairs of chromosomes. A division occurs producing 2 identical daughter cells.


What is differentiation?

The process by which stem cells become specialised to carry out a particular task.

In many animals, the cells become specialised very early in life. For example: when a muscle cell divides by mitosis- it can only form more muscle cells. 

In contrast, plant cells are able to differentiate all through their life. Undifferentiated cells are formed at active regions of the stems and roots. Mitosis takes place continuously.


What is meiosis?

Cells in the reproductive organs divide by meiosis to form the gametes (sex cells)


What happens in meiosis?

The genetic material is copied and then the cell divides twice NOT once like mitosis. Then, four gametes are formed by the division each with a single set of chromosomes.


What is variation?

Variation is a difference in the genetic material of an individual in order to enhance survival.


What can stem cells do?

Stem cells have the potential to treat previously incurable conditions. New nerve cells may be grown for people with brain disorders.

Scientists hope that the embryonic stem cells can be encouraged to grow into almost any different type of cell needed in the body. Some people believe that whole organs can also be grown from embryonic stem cells.


Problems with stem cells

Come from aborted embryos Ethical issues Violation of human rights Progress is slow; too much time and money used Embryos can not give permission


Benefits of stem cell research

One of the best ways to find cures for incurable conditions

Some embryos used come from infertility

Can be obtained by adult bone marrow Also obtained by the umbilical cord of the baby Can be used to grow new cells for transplants


What are chromosomes?

Thread like structures which are made up of large molecules of DNA.


What is a gene?

A gene is a small section of DNA which codes for a particular combination of amino acids that make proteins


What is DNA fingerprinting?

The use of the unique patterns in DNA to identify people


What is homozygous?

An individual with two identical alleles for a characteristic. Eg: DD or dd.


What is heterozygous?

An individual with different alleles for a characteristic. Eg; Dd


What is genotype?

The genetic make up of an individual


What is phenotype?

The physical appearance of an individual Eg: dimples or no dimples.


What is a carrier of a disease?

Someone who has the allele for a disease (recessive) but receives no symptoms of the disease.


Benefits of genetic screening?

•Able to identify if two people should have a baby •Ability to identify a disease before major effects take place Eg: Huntington's disease causes death to the middle age.


Disadvantages of genetic screening?

•Costs a lot of money •Takes up a lot of time •A long waiting time to get screened


Mitosis Diagram


Meiosis Diagram


Gregor Mendel and DNA:

Mendel was the first person to suggest separately inherited factors which we now call genes



Babies born with extra fingers or toes

Most common form caused by a dominant allele


Cystic Fibrosis:

Genetic disorder that affects many organs of the body

Organs become clogged up by thick, sticky mucus

Caused by a recessive allele so it needs to be inherited from both parents


Simple Punnett Square:


Huntington's Disease:

Inherited through a dominant allele

Causes death in the middle age