Cell cycle - DNA Replication BIO 120

Cell cycle:

DNA replication

Where does the cell cycle (DNA replication) take place

in the nucleus

Eukaryotic cell cycle

This cell cycle includes two distinct phases

Interphase and M phase

eukaryotic cell cycle phases

Interphase is broken down into 3 acive phases:

G1 S, and G2 

If a cell does not need to complete the cell cycle,
the cell enters ____

G0

Eukaryotic cell cycle has ______ chromosomes 

linear chromosomes

Yes, all DNA is composed of CTAG

M phase contains

mitosis and cytokinesis (division of the cytoplasm)

Where is DNA replicated?

S phase

Why are living organisms so different form one another?

The bases (CATG) are not the same percentages

How do we replicate DNA?

We seperate the helix to replicate DNA

What do the black dotted line indicate?

Hydrogen bonds

C and G result in how many hydrogen bonds?

3 hydrogen bonds

A and T result in how many hydrogen bonds?

2 hydrogen bonds

Semi conservative

each new duaghter DNA molecule has one strand that was parental and one strand that is new

Each parental strand is gonna act as a template for the ______ ______

New Strand

Helicase, topoisomerase, and primase are…

enzymes / proteins

Helicase

unwinds and separates parental DNA

Single-strand binding proteins

stabilize the unwound parental DNA strand

Topoisomerase

relieves the strain caused by unwinding 

In order for us to lay down new DNA bases we need a _____, that primer is made by ______, and it is a _____ primer

primer, primase, RNA

Primase

synthesizes RNA primer

DNA opens bubbles so that…

DNA doesn’t break

New strands of DNA are built from

5′ to 3′

DNA is ____ _____

anti parallel

What end is the 3 prime

Hydroxyl end

What end is the 5 prime

Phosphate end

You can only add a base to what prime

3 prime

The lagging strand builds _____

backwards

What number prime does the RNA primers stick to?

5 prime

Do we want RNA in our DNA?

no!

The short pieces in the lagging strand are referred to as

Okazaki fragments

____ _____ __ adds DNA bases to form the new strand of DNA

DNA Polymerase 3

In order to generate a single strand of replicated DNA on the lagging strand, two things must occur…

1.The RNA bases are
replaced with DNA bases
by DNA polymerase I.

2.DNA ligase joins the
fragments together by
completing the sugar-
phosphate backbone

Everytime our DNA replicates 

we get stagered ends on the lagging strand (there is a piece of DNA that cant be copied) 

DNA replication continually shortens one _____ _____ with each round of _____

DNA strand, replication

Telomeres

the ends of the chromosomes

• junk DNA 

• do not have genes

DNA replication has a _____ , and then they die

limit

In what specific kind of cells would losing telomeres be
problematic?

the cells that make egg and sperm (germ cells)

What proofreads the new daughter strand?

DNA polymerases

If DNA polymerase does not catch a mistake, mismatch repair takes palce via other… 

enzymes

Do errors in DNA occur only when DNA is copied?

• X-rays

• vultraviolet radiation (skin cancer)

• cigarette smoke (chemcial carcinogens) 

• spontaneous chemical changes