Chapter 3-27

What is the Cell Cycle?

is a series of changes a cell undergoes from the time it is formed until it reproduces.

There are 2 reasons why the cell go through the cell cycle.

1. To reproduce the organism

2. To grow and repair cells of a multicellular organism

What are the 2 major periods of the cell cycle?

• Interphase

• Cell division

What is the longest cell phase?

Interphase

What is the interphase of the cell cycle?

Period from cell formation to cell division, when cell carries out its routine activities and prepares for cell division

What is 2 main events for interface?

DNA Replication and Protein Synthesis

What is the state of nuclear material during interphase?

Uncondensed chromatin state.

Interphase consists of 3 parts:

G1 (Gap 1), S (Synthesis), G2 (Gap 2)

Interphase:

Explain what happens in G1 (Gap 1)

Vigorous growth and metabolism. Cell doubles the number of

organelles and accumulates materials needed for DNA synthesis

Interphase:

Explain what happens in S (Synthesis)

DNA replication occurs. Chromatid divides into 2 sister chromatids

Interphase:

Explain what happens in G2 (Gap 2)

Preparation for division. Cell synthesizes proteins that will help cell division.

What are checkpoints used for in cell division?

are key events in the cell cycle where cell division processes are checked and, if faulty, stopped until repairs are made.

What is the most important checkpoint out of the 3 in the cell cycle?

G1 checkpoint

What happens in the checkpoint g1 if it doesn’t pass?

If cell does not pass, it enters G0, in which no further division occurs. Cells that permanently cease dividing are in this phase

This phase can last from a few days to the rest of the cell’s life.

What is the first step the Interphase S phase does as it replicates the DNA?

DNA Helicase unwinds and unzips double-stranded DNA helices

Step two in the interphase S Phase:

What are the DNA polymerase job when the DNA helicase is unwinds and unzips its double strand?

• DNA Polymerase Immediately goes to work, and it clamps onto the open strands.

• It begins to add new nucleotides (Adenine, Thymine, Cytosine, Guanine) to create and add to the new DNA strand.

What is the third last step of interphase S Phase? End Result

There would be 2 identical “daughter” DNA molecules that are formed and they would be known as “Semiconservative replication”

The End result of Interphase S Phase: why is the “Semiconservative replication” called this way? And not a full “Replication”

Because each new double-stranded DNA is composed of one old strand and one new strand that was created by the DNA Polymerase.

What is mRNA function?

Carries the genetic materials in order to build the specific protein like hemoglobin. It is the recipe of the protein.

What are the 2 major steps that involve protein synthesis?

• Transcription

• Translation

Explain what happens in TRANSCRIPTION of protein synthesis in the cell cycle. Where in the interphase does it occur?

mRNA writes the whole code that was provided from the DNA. It would write the whole protein recipe by using RNA nucleotides instead of DNA. It only copies the recipe not the whole DNA strand

Happens in G1

What type of RNA are involved in TRANSLATION? where does it occur?

involves mRNA, rRNA, and tRNA. mRNA specifies the order of amino acids in a polypeptide

Happens in G2

What is the role of RNA?

RNA differs from DNA? Why?

RNA is the “go-between” molecule that links DNA to proteins

– RNA copies the DNA code in nucleus, then carries it into cytoplasm to ribosome

RNA differs from DNA

– Uracil is substituted for thymine in RNA

– RNA has ribose instead of deoxyribose suga

RNA has 3 types:

mRNA-

rRNA-

tRNA-

explain each process and what they do?

mRNA- Copies the protein recipe from the DNA. This process is called “Transcription”

rRNA- rRNA are the ones that receive the protein recipe from mRNA to create the actual protein. using the help of tRNA. They are the “factory”.

tRNA- Have special areas that contain a specific triplet code (anticodon) that allows each tRNA to carry only a specific amino acid

• Anticodon of tRNA will complementary base-pair with codon of mRNA at ribosome, adding its specific amino acid to growing polypeptide chain

 Process is referred to as TRANSLATION

Do mRNA transcribes all proteins?

No not all as it sometimes rejects it to not make it.