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Module 2.2/2.3

During a mitotic cell cycle genetic information (DNA) is copied and passed genetically identical
cells.

In gamete cell formation (meiosis) halving the DNA independent segregation and crossing over
give non identical cells (variety).

Be able to analyse, interpret and evaluate data that shows DNA to be the genetic…

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Originally, the term mitosis refers only to nuclear division unaccompanied by cytokinesis (which
is the division of the cytoplasm), as in the case of some cells like certain fungi and in
fertilized egg of many insects. As used now , mitosis used interchangeably with cell division.



Replication: The process of…

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acids and untranslated sequences. The introns are removed and the exons are joined together to form
the final functional mRNA .




Stage Main Events
Interphase Cell makes a copy of its chromosomes by
replication of DNA cell grows and undergoes its
normal physiological functions.




Prophase Chromosomes coil, becoming shorter and…

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optical microscope. Cytoplasm divides to form
2 new cells.




Importance of mitosis:

1. Growth: mitosis ensures that new cells can be formed with identical genetic material to
the parent cell.
2. Repair: if cells are damaged or die they must be replaced with cells that perform the same
functions as…

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3. They grew bacteria in growth medium with 15
N then transferred them to 14N for one
generation. DNA extracted and spun in caesium chloride.

Supports semi-conservative replication.




Meiosis ­ seperates homologous chromosomes and produces haploid cells:

Homologous chromosomes

Members of each pair
Controlling the same character in the same…

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Gametes have a mixture.

Each gene can have different alleles in homologous pairs.

Genetic recombination by crossing over.

During the first meoitic division, the members of each homologous pairs lie side by side. If
they break at the same point along their length, the broken segment can join the other…

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Notes from revison guide:

Dna is made of nucleotides that contain a sugar, a phosphate and a base.

1. DNA is a polynucleotide ­ it's made up of lots of nucleotides joined together.
2. Each nucleotide is made from a pentose sugar, a phosphate group and a nitrogenous base.
3.…

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The nature and development of organisms is determined by genes:

1. Enzymes speed up most of our metabolic pathways ­ the chemical reactions that occur in
the body. These pathways determine how we grow and develop.
2. Because enzymes control the metabolic pathways, they contibute to our development,
and ultimately…

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