Introduction to Genetics Genetics is all about DNA DNA is located in the nucleus of cells. The actual pieces of DNA are called chromosomes. Chromosomes contain the genetic code for everything (traits). Chromosomes are not visible until they are ready to “divide/reproduce” In humans, 46 is the magic number.
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Introduction to Genetics Genetics is all about DNA Genetics is all about DNA DNA is located in the nucleus of cells. DNA is located in the nucleus of cells.
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Introduction to Genetics
Genetics is all about DNA DNA is located in the nucleus of cells. The actual pieces of DNA are called
chromosomes. Chromosomes contain the genetic
code for everything (traits). Chromosomes are not visible until
they are ready to “divide/reproduce” In humans, 46 is the magic number.
Reproduction
Reproduction
Making new individuals from an existing individual
How??
Chromosomes copy themselves and then “split” creating a new cell.
Common among plants and consists of certain parts that grow out from a main parent plant and eventually root and sprout to form new, independent plants.
Examples: strawberry
Mitosis In animals (humans) this form of
reproduction is used in “body cells.” Example : Skin cells must be
replenished Constant process The DNA of the cell copies itself and
then splits using a process called mitosis creating a new cell identical to the original
1 cell with 46 chromosomes – doubles (92) – splits into 2 cells with 46 chromosomes each (identical)
Example of Mitosis:
Root Cells of a Broad Bean (Vicia faba)
In the "resting" phase the chromosomes are not obvious within the
nucleus.
Just before cell division starts, a lot of
metabolic activity occurs, the
chromosomes start to gradually shorten and
thicken.
Each chromosome has divided to
produce 2 identical chromatids, joined at a structure called the centromere.
They begin to move towards the equator
of the cell.
Once at the equator of the cell, the
centromeres attach to threads of a spindle
structure that has formed. (The spindle
spans from one end of the cell to the other).
Contraction of the spindle fibers begins
to cause the chromatids to pull
apart from one another and move towards opposite ends of the cell.
The chromatids separate further. Energy for this is
provided by mitochondria.
A new nuclear membrane begins to
form round the 2 groups of chromatids. A new cell wall begins