Class Starter
Each time a cell reproduces, it divides into two new cells. When each of the new cells
divide, the result is four new cells. If this continues, how many cells will be present after
the cells reproduce 6 times?
Objectives
• Why do cells divide?
• How is DNA packaged into the nucleus?
• How do cells prepare for division?
10.1: Cell Reproduction
Why Cells Reproduce
• the body of a multicellular organism grows larger by ______________________.
•
New cells are needed to
– help
– Replace
– Replace
Cell Size
• A cell’s ability to exchange substances is limited by its _____________________
•
As a cell gets larger, substances must travel _____________ to reach where they
are needed.
Cell Maintenance
• The work of cells is done by _______________. As a cell gets larger, more
proteins are required to __________________________________.
•
Cell size is also limited by the cell’s _________.
– If the cell gets too large, DNA instructions cannot be copied quickly
enough to make the ______________ that the cell needs to support itself.
Making New Cells
• Each “daughter” cell has a ___________ surface area–to-volume ratio than its
parent does.
•
Each new cell also gets an __________________ of the cell’s DNA.
•
Because ________________cells are more difficult to maintain, cells _________
when they grow to a certain size.
Checkpoint
•
How does the body grow bigger?
•
Give 2 reasons why new cells are needed.
•
What are 2 factors that effect cell size?
•
What effect does DNA have on cell size?
•
What does each new daughter cell require?
Chromosomes
• The large molecule of DNA is organized into hereditary units called __________.
•
A gene is a segment of _________ that codes for _______and _______________.
•
Each cell has a large amount of DNA that must be
condensed into a very small volume.
•
DNA is organized and packaged into structures called ____________________.
Prokaryotic Chromosomes
• A prokaryotic cell has a __________ circular molecule of DNA.
•
This loop of DNA contains ________________ of genes.
•
A prokaryotic chromosome is condensed through repeated ______________ or
________________, like a rubber band twisted upon itself many times.
Eukaryotic Chromosomes
• Eukaryotic cells contain ________________________ arranged on several
_________________________ molecules.
•
Eukaryotic DNA into highly condensed ___________________ structures with
the help of many ________________.
•
The DNA and proteins make up a substance called ____________________.
Checkpoint
•
What is another name for hereditary units?
–
What is it composed of?
•
DNA is organized and packaged into _____.
•
What is the difference between prokaryotic and eukaryotic chromosomes?
Eukaryotic Chromosomes (cont.)
• The first level of packaging is done by a class of proteins called ______________.
•
The long DNA molecule is wound around a series of histone cores in a regular
manner and is called a _________________________.
•
Nucleosomes coil to form ___________________
•
Chromatin loops and coils to form a ____________________
•
As the cell prepares to divide, the chromosomes _______________ even further
ensuring that the extremely long DNA molecules __________________________
during cell division.
•
Each of the two thick strands of a fully condensed, duplicated chromosome are
called a _______________________.
•
Each chromatid is made of a ________________________________________.
•
Identical pairs, called _______________________, are held together at a region
called the _________________________.
•
During cell division, the sister chromatids are separated at the _______________,
and one ends up in each __________________________.
•
Each new cell has the same __________________________ as the parent cell.
Checkpoint
•
Organize the following in the order of organization: chromosome, nucleosome,
and chromatin.
•
Why does DNA condense when it is about to divide?
•
–
What is it called?
–
What holds it together?
Each sister chromatid ends up in a _________ ________ producing 2 _______
cells.
Preparing for Cell Division
• All new cells are produced by the ______________________________________.
•
All newly-formed cells require ________, so before a cell divides, a copy of
_________ is made for each daughter cell.
•
Each new cells will function in the ______________ as the cells that they replace.
Prokaryotes
• In prokaryotic cells, the __________________ molecule is attached to the inner
_______________________________.
•
The cytoplasm is divided when a new cell membrane forms _________________
__________________. Meanwhile the cell continues to grow until it nearly
_________________________.
•
Eventually the dividing prokaryote is pinched into two independent
________________________, each of which has its own circular
DNA molecule.
Eukaryotes
• The reproduction eukaryotic cells is more ___________________ than that of
prokaryotic cells.
•
The DNA within the nucleus must also be ____________, _____________, and
_____________________.
Checkpoint
•
What must occur before the cell divides and why?
•
Summarize the process in which a prokaryotes divide into 3 steps.
–
What is this process called?
•
How does prokaryotic division compare to eukaryotic division?
•
What happens to DNA in eukaryotic division?
Summary
• Because larger cells are more difficult to maintain, cells divide when they grow to
a certain size.
• Many proteins help package eukaryotic DNA into highly condensed chromosome
structures.
• All newly-formed cells require DNA, so before a cell divides, a copy of its DNA
is made for each daughter cell.