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What is the grey dust?

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What is the grey dust? - PowerPoint PPT Presentation


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The way we are and our traits comes from our genes . Genes are on long chemicals called DNA . DNA is four chemicals . It is very long and very thin, about 1 billion times longer than it is wide . DNA is found in the nucleus of the cell . DNA is shaped like a double helix.

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Presentation Transcript
slide1
The way we are and our traits comes from our genes. Genes are on long chemicals called DNA. DNA is four chemicals. It is very long and very thin, about 1 billion times longer than it is wide. DNA is found in the nucleus of the cell. DNA is shaped like a double helix.
slide3

slide4
Cells are always replicating (复制). Sometimes it is to make a baby. Sometimes it is just to make new cells inside your body.

Today we are talking about cells

replicating INSIDE your body.

the dna ladder is made of 4 different nitrogen bases a adenine g guanine c cytosine t thymine
The DNA ladder is made of 4 different nitrogen bases:A (adenine) G (guanine)C (cytosine)T (thymine)
a always joins with t
A always joins with T

C always joins with G

Play game…

there are three kinds of mutations
There are three kinds of mutations:

Deletion: (one pair of letters in gone)

Addition: (one more pair of letters comes)

Substitution: (one pair is changed for

a different one)

cancer cells
Cancer cells:

1. Do not work like regular cells.

2. They “steal” nutrients from other cells.

3. The nucleus is larger than other cells.

slide16
Some scientists say that smoking only 15 cigarettes can change a persons DNA. If that is true, why don’t all people who smoke cigarettes have cancer?
not all tumors are cancerous they don t hurt other cells or spread to other parts of the body
Not all tumors are cancerous. They don’t hurt other cells or spread to other parts of the body.

Benign

slide19
Sometimes, tumors can grow so big they hit blood vessels. Then they send cancer cells to other parts of the body.

Metastasis

so how to cure cancer
So, how to cure cancer?

Chemotherapy (化疗) gives a very

Powerful drug through

an intravenous drip (IV drip)

The drug kills cancer cells

but also kills regular cells.

how does the candy represent survival of the fittest1
How does the candy represent survival of the fittest?

What is the candy’s environment?

What are the predators (大鳄)?

The candies’ environment is the classroom.

The predators are us.

how does the candy represent survival of the fittest2
How does the candy represent survival of the fittest?

Which candies are the fittest?

The candies that are not delicious are

the fittest because they

survived the best.

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