Chapter 5.1 Notes

Chapter 5 

Cell Growth and Division 


Cell Growth and Division 

Why It’s Important 

Cells must copy 

their chromosomes 

and divide properly in 

order to make new 

cells that function 

________________ 

properly 

4-day old mouse cells 

Chapter menu 

Resources 

Copyright © by Holt, Rinehart and Winston. All rights reserved.


Objectives 

• Identify four examples of cell division in eukaryotes 

and one example in prokaryotes. 

• Differentiate between a gene, a DNA molecule, a 

chromosome, and a chromatid. 

• Differentiate between homologous chromosomes, 

autosomes, and sex chromosomes. 


Resources 



Formation of New Cells by Cell Division 

reproduction 

• Cell division, also called cell _________________, 

occurs in humans and other organisms at different 

times in their life 

repair 

________ 

growth 

__________ 


Resources 


• Before a cell can divide, the DNA must first 

be __________ copied and then _______________ 

distributed 

to new cells 

• Why does each new cell need an identical 

copy of DNA? 

DNA codes for the proteins made by 

the cell…incorrect DNA will lead to 

altered proteins 


Resources 


• Prokaryotes carryout a very simple type 

of cell division called ______________ binary 

___________ fission 

– Occurs in two stages: 

• 1st DNA is _____________ 

copied 

• 2 nd the original cell divides 

into _______ two new cells 


Resources 


• The original cell divides by adding 

a new cell _____________ 

membrane 

between the copied DNA 

• As new material is added, the 

membrane _________ pinches in 

• Next, a new cell ____________ wall 

forms around the membrane 

• Last, the original cell pinches off 

into two _______________ identical cells 


Resources 


• Binary fission is a form of _________________ 

reproduction because…. 

single 

– It only involves a _____________ parent that 

passes ___________ exact copies of its DNA to its 

offspring 

exact 

asexual 

– So the offspring are __________ copies of the 

parent prokaryotic cell. 


Resources 


Eukaryotic Cells 

• Before eukaryotic cells divide, their 

DNA is ____________ uncoiled and referred 

to as _______________ 

chromatin 

double 

• Recall that DNA is a _____________ 

helix made up of subunits called 

_________________ 

nucleotides 


Resources 


• Your DNA is normally uncoiled 

because the _________ code it contains is 

being used to make 

_______________ 

proteins 

• Recall that specific segments of your 

DNA, called ___________, genes code for 

the production of _____________ different 

proteins 


Resources 


• Before a eukaryotic cell divides, the DNA is 

____________, copied and it __________ coils up to form a 

chromosome 

• First, DNA coils around 

histones 

proteins called _________ 

to form small structures 

nucleosomes 

called ______________ 

nucleosome 


Resources 


• Next, the nucleosomes actually end up coiling 

__________ twice on themselves to form a 

_________________ 

supercoil 


Resources 


• This supercoil is tightly packed in a structure called a 

________________ 

chromosome 


Resources 


• Chromosomes have two 

________________ identical sides 

because they contain DNA that 

has already been ____________ copied 

• Each side is called a sister 

_____________ chromatid and they are 

attached at a point called a 

_________________ 

centromere 


Resources 


• These sister chromatids 

_______________ separate at the 

centromere during cell division to 

ensure that each new cell has the 

_________ same genetic information as 

the original cell 


Resources 



Different species 

contain different 

numbers of 

chromosomes 

Ex: Humans 

have ______ 46 

chromosomes 

while a dog has 

_______ 78 

chromosomes 


Resources 


Asexual Reproduction – Eukaryotic cells 

exact 

• Eukaryotic cells will make _________ copies of 

themselves during asexual reproduction for four 

different types of cell division 

– One type is simply for ___________________ 

– Eukaryotes may also make new cells for 

_________________, repair ________________, growth or 

_____________________ 

development 

reproduction 


Resources 


• Asexual reproduction only occurs in body cells which are 

also called ___________________ cells 

• Examples of somatic cells are _______________, 

_____________, and ________________ cells 

muscle 

• You want these new cells to do the same job as their 

parent cell, so it is good that they make exact 

__________of each other 

copies 

somatic 

skin 

nerve 

• Overtime…the ends of your DNA strands start to 

deteriorate so your cells ______ age and change slightly even 

though they are “copies” 


Resources 


46 

• All of your somatic cells contain ____ chromosomes, 

which means they are _________ diploid cells 

• A diploid cell is mathematically written as ______, 

which means they have two _______ sets of 

chromosomes… 

mother 

2n 

– you inherit one set from your _____________ and 

____________ father 


Resources 


Sexual Reproduction – Eukaryotic Cells 

One 

• ______ pair of your chromosomes are called your 

_______ sex chromosomes, because they are involved 

with determining your ____________ gender 

• Your other 22 pairs of chromosomes are called 

________________ 

autosomes 


Resources 


• Your two sex chromosomes are referred to as _____ 

and _____ Y 

– You inherit one from each parent 

• ______ XY = male 

• ______ = female 

XX 

• Females can donate only X’s while males can donate 

an X or a Y… 

• Do males or females determine the sex of an 

offspring? 

males 

X 


Resources 


Objective 1 

• Identify four examples of cell division in eukaryotes 

and one example in prokaryotes. 

Binary fission 

reproduction 

repair 

growth 

development 


Resources 


Objective 2 

• Differentiate between a gene, a DNA molecule, a 

chromosome, and a chromatid. 

Gene – Segment of a DNA that codes for a protein 

Chromosome – coiled DNA molecule (x shape 

means it has been copied already) 

Chromatid – identical copy of DNA found in a 

chromosome…held together by 

centromeres 


Resources 


Objective 3 

• Differentiate between homologous chromosomes, 

autosomes, and sex chromosomes. 

Homologous 

(22 Pairs) 

Nonhomologous… 

determine gender 

Similar in 

structure 


Resources

Chapter 5.1 Notes

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