Sect ion: 2.1 Name:

Opening Act iv i ty :

Latin Root Word

Rev iew of Old Informat ion: None

New Informat ion: Notes - Chromosomes and the Cell Cycle Why ce l l d iv is ion? A.Necessary for the __________ of organisms. B.Necessary for every cell in organism to have the ___________ instructions to survive. C.Genetic instructions passed through __________ in _______________. DNA. A. Cell reproduction begins with _______. B. DNA is a long, thin molecule stores _________ information! C. Found in _____________ of eukaryotic cells. What are chromosomes A.Rod-shaped structures of coiled ________ and ___________. B.____________: proteins in chromosomes that help DNA form its double helix shape. C.____________: proteins that control activities of DNA

I. Chromosome  Structure  a. ______________  –  condensed  DNA  that  can  be  found  in  the  nucleus  of  the  cell  during  cell  

division  –  visible!  i. Remember,  Chromatin  is  uncondensed  DNA  and  cannot  be  seen.  

b. The  DNA  in  a  chromosome  can  be  found  wrapped  around  proteins  known  as  _______________  

 

c. Chromosomes  have  two  halves  known  as  ______________________.  

 

d. The  ________________________  holds  the  two  halves  of  the  chromosome  together.    

e. Sex  Chromosomes  –  Chromosomes  that  determine  the  sex  of  an  organism  i. In  humans,  the  sex  chromosomes  are  ______________________  

1. Women  have  two  X  chromosomes  2. Men  have  an  X  chromosome  and  a  Y  chromosome  

f. _________________________  –  any  non-­‐sex  chromosome  i. __________________________________________  –  the  two  copies  of  each  autosome  

g. __________________________  –  a  photo  of  the  homologous  chromosomes  found  in  humans  

 

h. ______________________  –  Have  both  sets  of  homologous  chromosomes  i. Each  chromosome  has  a  pair  ii. In  humans  this  means  ________chromosomes  

i. ______________________  –  have  just  one  set  of  homologous  chromosomes  i. Each  chromosome  doesn’t  have  it’s  pair  ii. In  humans  this  means  ________  chromosomes  

The Cel l Cyc le and Cancer :

A.Cell division occurs during the ___________________

B.It is the repeating set of events that make up the life cycle of a cell.

C.Divided into __________ phases:

1._____________: time between cell divisions

2.Cell Division: consists of two stages

a._______________: division of nucleus.

b._______________: division of cytoplasm of the cell.

Stages of Interphase

1. G1 Phase: _____________________.

2. S Phase: ____________________.

3. G2 Phase: growth and ________________ for cell division (organelles develop)

***G0 Phase: used by some cells to exit cell cycle; usually occurs after G1 Phase; examples include mature nerve cells.

CANCER

Cancer is a disease of the ____________. Some of the body’s cells divide uncontrollably and _______________ form.

Some Tumors are cancer others are not

___________________

¨Cells in a tissue overgrow

¨Resulting defined mass: ________________ (neoplasm)

-________________, e.g., moles

1. _________ growth

2. Expands in the same tissue; does ________ spread

3. Cells look nearly normal

-________________

1. ___________ growth

2. Invades surrounding tissue and ________________(becomes cancerous)

3. Cell differentiation usually poor

Cancer ce l ls do not d iv ide normal ly

¨Cancer cells don’t necessarily divide faster than normal cells; more cancer cells are ___________________ than dying

¨Cancer cells do not respond to _____________; loss of ____________ inhibition

1. Leads to a disorganized mass; cells may have extensions

2. ___________: makes a cancer malignant

Cancer usua l ly invo lves severa l genes

¨______________________

-In ________________ cells

-Code for proteins involved in the ____________ of cell division

-If altered, may form ____________

-_____________, do not cause malignant cancer

-Require other mutations, including one in a tumor suppressor gene

¨_______________________

-_________ cell growth and _________; __________ cancer formation

-May prevent expression of ____________________

-p53: codes for a regulatory protein that turns off cell division when the cell is stressed or damaged

1. If mutated, runaway ____________________

2. More than _________ of cancers has a mutated or missing p53 gene

Factors that may lead to cancer…

Treatment for cancer ce l ls…

Act iv i ty :

Read pages 145 through 147 and answer the following questions

1. Draw the structure of a chromosome labeling the DNA, centromere, chromatid.

2. Describe the difference between a chromosome and a DNA molecule?

3. _____During cell division, the DNA in a eukaryotic cell is tightly packed and coiled into structures called

a. centromeres b. histones c. haploids d. chromosomes

4. _____Between cell divisions, the DNA in a eukaryotic cell is uncoiled and spread out; in this form it is called

a. chromatid b. chromatin c. histone d. nonhistone

5. _____The chromosomes of most prokaryotes consist of proteins and

a. a single circular DNA molecule

b. a single linear DNA molecule

c. a pair of linear DNA molecules joined in the center

d. a pair of homologous, circular DNA molecules

6. What are homologous chromosomes?

7. Humans have 46 chromosomes in all cells except sperm and egg cells. How many of these chromosomes are autosomes?

8. Compare chromosomes and chromatids.