Embed Size (px)
Citation preview
Getting Through
Materials move through cells by diffusion. Oxygen and food move into cells, while waste products move out of cells. How does the size of a cell affect how efficiently materials get to all parts of a cell?
Work with a partner to complete this activity. Rulers can be found on the front counter.
1. On a sheet of paper (scratch paper), draw a cell that has the following dimensions: 5 cm x 5 cm x 5 cm. Your partner should draw another cell about one half the size of your cell.
2. Compare your drawings. How much longer do you think it would take to get from the cell membrane to the center of the big cell than from the cell membrane to the center of the smaller cell?
3. What is the advantage of cells being small?
10-1 Cell Growth
• Do larger organisms have larger cells?
10-1 Cell Growth
• Do larger organisms have larger cells?
• No, they just have more cells
10-1 Cell Growth
• Cells divide for 2 reasons
1.DNA Overload – larger cells place more
demands on DNA
• DNA – the information that controls a
cells function
• When cells are small, the DNA can take
care of the cells needs
10-1 Cell Growth
10-1 Cell Growth
10-1 Cell Growth
10-1 Cell Growth
10-1 Cell Growth
10-1 Cell Growth
• Cells divide for 2 reasons
2.Exchanging Materials – Larger cells have
more trouble with transporting nutrients and
wastes
Cell Size
Surface Area
Volume
Ratio of Surface
Area to Volume
Surface Area = L x W x 6
Volume = L x W x H
10-1 Cell Growth
• Cell Division – cell divides into 2 “daughter
cells”
– Cell copies it’s DNA (Replication)
– Then splits in 2
10-2 Cell Division
• Cell Division occurs in 2 stages
– Mitosis – division of nucleus and DNA
– Cytokinesis – division of cytoplasm
– Unicellular organisms – method of
reproduction (asexual), produces 2 genetic
clones
– Multicellular organisms – results in growth
10-2 Cell Division
• Chromosomes & DNA
– Strands of DNA wrapped around proteins
– Only visible during division
– Humans have 46
– Cells have to ensure that each new cell is going to get a complete copy of DNA before dividing
10-2 Cell Growth
• Cell Cycle
– Interphase – the longest part of the cell cycle
• G1 – cell grows
• S – chromosomes (DNA) are replicated (copied)
• G2 – organelles for the new cell are produced
M phase
G2 phase
S phase
G1 phase
Chromosomes
•Chromosomes = DNA
– DNA is coded instructions that
– Chromosomes are tightly coiled strands of DNA
•Chromosomes are easy to move around (like during mitosis), but can’t be read
•DNA can be read, but is hard to move around
10-2 Cell Growth
• Cell Cycle
– Mitosis – the shortest part of the cell cycle;
the process of cell division
• Prophase
– DNA condenses into chromosomes
– Chromosomes attach to spindle fibers
– Nuclear membrane breaks down
10-2 Cell Growth
• Cell Cycle
– Mitosis – the shortest part of the cell cycle;
the process of cell division
• Metaphase
– Chromosomes line up across the
center of the cell
10-2 Cell Growth
• Cell Cycle
– Mitosis – the shortest part of the cell cycle;
the process of cell division
• Anaphase
– Chromosomes are pulled apart and
move to opposite ends of the cell
10-2 Cell Growth
• Cell Cycle
– Mitosis – the shortest part of the cell cycle;
the process of cell division
• Telophase
– Chromosomes begin to un-condense
– Nuclear membrane reforms
10-2 Cell Growth
• Cell Cycle
– Mitosis – the shortest part of the cell cycle;
the process of cell division
• Cytokinesis
– Separation of the cytoplasm and
organelles
Interphase
Cytokinesis
Telophase
Anaphase
Metaphase
Prophase
MITOSIS
Knowing When to Stop
Suppose you had a paper cut on your finger. Although
the cut may have bled and stung a little, after a few
days, it will have disappeared, and your finger would be
as good as new.
1. How do you think the body repairs an injury, such as a cut on a finger?
2. How long do you think this repair process continues?
3. What do you think causes the cells to stop the repair process?
10-3 Regulating the Cell Cycle
• What regulates how fast cells divide or if cells
divide? How do they know when it’s time to
divide?
10-2 Cell Growth
• Cyclins – protein that regulates the cell cycle
(cycle – cyclins… get it?)
– Make sure cells don’t divide until all
chromosomes have been regulated
– Make sure cells don’t enter anaphase until
chromosomes are attached to spindle
10-2 Cell Growth
• What happens when these regulator proteins fail in their job?
• Cancer – when cells lose the ability to control growth and division; cells stop responding to the regulator signals
– Tumors
– Many cancers caused by mutation in the gene called P53
• Malfunction of the protein that stops cells dividing if all DNA isn’t replicated
Analyzing Data: Life Spans of Human
Cells (pg 249)
Independently, answer questions 1-4 on a
separate piece of paper.
