Chapter 5 The Cell in Action

Section 1: Exchange with the Environment  A cell must be able to obtain energy and raw materials and get rid of wastes  This exchange of materials takes place at the cell’s membrane  A cell must be able to obtain energy and raw materials and get rid of wastes  This exchange of materials takes place at the cell’s membrane

What is Diffusion?  Matter is made up of tiny particles  Particles of matter are always moving and colliding with each other  Particles naturally travel from areas where they are crowed to areas where they are less crowded - diffusion  Diffusion - the movement of particles from an area of high concentration to an area of low concentration  Matter is made up of tiny particles  Particles of matter are always moving and colliding with each other  Particles naturally travel from areas where they are crowed to areas where they are less crowded - diffusion  Diffusion - the movement of particles from an area of high concentration to an area of low concentration

Diffusion of Water  All organisms need water to live  Cells are surrounded by and filled with fluids (mostly water)  The movement (diffusion) of water through the cell membrane is called osmosis  Because osmosis is diffusion, water moves from areas of high concentration to areas of low concentration AAll organisms need water to live CCells are surrounded by and filled with fluids (mostly water) TThe movement (diffusion) of water through the cell membrane is called osmosis BBecause osmosis is diffusion, water moves from areas of high concentration to areas of low concentration

 Like animal cells, plant cells also take in and release water by osmosis  What would happen to a grape if you placed it in a dish of pure water?  What would happen to it if you placed it in water mixed with a large amount of sugar?  Like animal cells, plant cells also take in and release water by osmosis  What would happen to a grape if you placed it in a dish of pure water?  What would happen to it if you placed it in water mixed with a large amount of sugar?

Moving Small Particles Moving Small Particles  Many particles are too large to “slip” past the molecules of the cell membrane  i.e. amino acids and sugars must pass through protein “doorways” located within the membrane  They can travel through these proteins either by passive or active transport  Many particles are too large to “slip” past the molecules of the cell membrane  i.e. amino acids and sugars must pass through protein “doorways” located within the membrane  They can travel through these proteins either by passive or active transport

 Passive transport - is the diffusion of particles through membrane proteins  This does not require energy  Active transport - is the movement of particles through membrane proteins against the normal direction of diffusion  This requires energy (ATP)  Passive transport - is the diffusion of particles through membrane proteins  This does not require energy  Active transport - is the movement of particles through membrane proteins against the normal direction of diffusion  This requires energy (ATP)

Moving Large Particles  The cell can also move particles into and out of the cell that are too large to pass through membrane proteins  Endocytosis - when the cell membrane surrounds a particle and encloses it in a vesicle  Exocytosis - vesicles are formed carrying particles to the cell membrane to be removed  The cell can also move particles into and out of the cell that are too large to pass through membrane proteins  Endocytosis - when the cell membrane surrounds a particle and encloses it in a vesicle  Exocytosis - vesicles are formed carrying particles to the cell membrane to be removed

Section 2: Cell Energy  Why do you get hungry?  Feeling hungry is your body’s way of telling you that your cells need energy  FROM SUN TO CELL  All energy that fuels life comes from the sun  Plants are able to capture the energy of the sun and store it in sugars (glucose)  Why do you get hungry?  Feeling hungry is your body’s way of telling you that your cells need energy  FROM SUN TO CELL  All energy that fuels life comes from the sun  Plants are able to capture the energy of the sun and store it in sugars (glucose)

Photosynthesis  The process of capturing light energy and changing it into food is called - photosynthesis  Photosynthesis means “made by light”  Plants have molecules in their cells that capture light - pigments  Chlorophyll - the main pigment found in plant cells  Chlorophyll is found in the chloroplasts  The process of capturing light energy and changing it into food is called - photosynthesis  Photosynthesis means “made by light”  Plants have molecules in their cells that capture light - pigments  Chlorophyll - the main pigment found in plant cells  Chlorophyll is found in the chloroplasts

 Plants use the energy captured by chlorophyll to change carbon dioxide (CO 2 ) and water (H 2 0) into food (C 6 H 12 O 6 ) and oxygen (O 2 ).  Glucose (C 6 H 12 O 6 ) is a carbohydrate.  The glucose can be used by the plant or stored as energy in the form of other carbohydrates or lipids.  Plants use the energy captured by chlorophyll to change carbon dioxide (CO 2 ) and water (H 2 0) into food (C 6 H 12 O 6 ) and oxygen (O 2 ).  Glucose (C 6 H 12 O 6 ) is a carbohydrate.  The glucose can be used by the plant or stored as energy in the form of other carbohydrates or lipids.

Getting Energy from Food  Cells get energy from the food you eat  But they can’t get it directly from a banana or a piece of pizza  All organisms must break down food molecules in order to release energy  There are two ways to do this:  1) Cellular Respiration  2) Fermentation  Cells get energy from the food you eat  But they can’t get it directly from a banana or a piece of pizza  All organisms must break down food molecules in order to release energy  There are two ways to do this:  1) Cellular Respiration  2) Fermentation

Cellular Respiration  Most organisms use cellular respiration to obtain energy that is stored in food  C.R. breaks down glucose, in the presence of oxygen, into carbon dioxide and water, which releases energy  This energy is then converted and stored as ATP, which is eventually used by the cells  Most organisms use cellular respiration to obtain energy that is stored in food  C.R. breaks down glucose, in the presence of oxygen, into carbon dioxide and water, which releases energy  This energy is then converted and stored as ATP, which is eventually used by the cells

 Does the equation for respiration remind you for the equation for photosynthesis?  Let’s take a look DDoes the equation for respiration remind you for the equation for photosynthesis? LLet’s take a look

Fermentation  Have you ever run so far or fast that your muscles start to burn?  This happens because your muscle cells can’t get the O 2 it needs to produce ATP by cellular respiration  Your body then uses fermentation  Fermentation leads to the production of a small amount of ATP  There are two types:  1) Lactic Acid - occurring in your muscles  2) Alcoholic - occurring in bacteria and yeast  Have you ever run so far or fast that your muscles start to burn?  This happens because your muscle cells can’t get the O 2 it needs to produce ATP by cellular respiration  Your body then uses fermentation  Fermentation leads to the production of a small amount of ATP  There are two types:  1) Lactic Acid - occurring in your muscles  2) Alcoholic - occurring in bacteria and yeast

Section 3: The Cell Cycle  In the time it takes you to read this sentence, your body will have produced a millions of new cells!  Producing new cells allows you to grow and replace cells that have died  i.e. The environment in your stomach is so acidic that the cells lining it have to be replaced every week!  In the time it takes you to read this sentence, your body will have produced a millions of new cells!  Producing new cells allows you to grow and replace cells that have died  i.e. The environment in your stomach is so acidic that the cells lining it have to be replaced every week!

The Life of a Cell  Cell cycle - the life cycle of a cell  The cell cycle begins when the cell is formed and ends when the cell divides to form a new one  Before a cell divides it must make an exact copy of all its DNA and organelles  DNA in a cell is organized into structures called chromosomes  Cell cycle - the life cycle of a cell  The cell cycle begins when the cell is formed and ends when the cell divides to form a new one  Before a cell divides it must make an exact copy of all its DNA and organelles  DNA in a cell is organized into structures called chromosomes

Making More Prokaryotic Cells  Prokaryotic cells (bacteria) and their DNA are not very complex  Bacteria have ribosomes and a singular circular DNA  Because of this division of bacteria cells is simple - binary fission  Binary fission means “splitting in two”  Prokaryotic cells (bacteria) and their DNA are not very complex  Bacteria have ribosomes and a singular circular DNA  Because of this division of bacteria cells is simple - binary fission  Binary fission means “splitting in two”

Eukaryotic Cells and Their DNA  Eukaryotic cells are much larger and more complex than prokaryotic cells  Because of this eukaryotic cells have a lot more DNA  The total number of chromosomes in eukaryotic cells varies from organism to organism  i.e fly - 8, potato - 48, and human - 46 (23 pairs)  Pairs of similar chromosomes are called homologous chromosomes  Eukaryotic cells are much larger and more complex than prokaryotic cells  Because of this eukaryotic cells have a lot more DNA  The total number of chromosomes in eukaryotic cells varies from organism to organism  i.e fly - 8, potato - 48, and human - 46 (23 pairs)  Pairs of similar chromosomes are called homologous chromosomes

Making More Eukaryotic Cells  The eukaryotic cell cycle has three main stages  In the first stage, the cell grows and copies its organelles and chromosomes (DNA)  After each chromosome is duplicated, the two copies are held together at a region called the centromere and are called chromatids  The eukaryotic cell cycle has three main stages  In the first stage, the cell grows and copies its organelles and chromosomes (DNA)  After each chromosome is duplicated, the two copies are held together at a region called the centromere and are called chromatids

 In the second stage, the chromatids separate  The complicated process of chromosome separation is called mitosis  Mitosis ensures that each new cell receives a copy of each chromosome  Mitosis can be divided into four phases  In the third stage of the cycle, the cell divides and produces two cells that are identical to the original cell  In the second stage, the chromatids separate  The complicated process of chromosome separation is called mitosis  Mitosis ensures that each new cell receives a copy of each chromosome  Mitosis can be divided into four phases  In the third stage of the cycle, the cell divides and produces two cells that are identical to the original cell

Mitosis and the Cell Cycle  Although mitosis is a continuous process, it can be divided into four phases;  Phase 1 - prophase  Phase 2 - metaphase  Phase 3 - anaphase  Phase 4 - telophase  Although mitosis is a continuous process, it can be divided into four phases;  Phase 1 - prophase  Phase 2 - metaphase  Phase 3 - anaphase  Phase 4 - telophase

Before Mitosis  Before mitosis begins, the chromosomes, organelles, and centrioles are copied.  Each chromosome now consists of two chromatids  Before mitosis begins, the chromosomes, organelles, and centrioles are copied.  Each chromosome now consists of two chromatids

Mitosis Phase 1  The nuclear membrane breaks apart  The two centrioles move to opposite sides of the cell  Fibers form from the centrioles and attach to the centromeres  The nuclear membrane breaks apart  The two centrioles move to opposite sides of the cell  Fibers form from the centrioles and attach to the centromeres

Mitosis Phase 2  The chromosomes line up in the middle (equator) of the cell

Mitosis Phase 3  The chromatids separate and are pulled to opposite sides of the cell by the fibers attached to the centrioles

Mitosis Phase 4  A nuclear membrane forms around each set of chromosomes  The fibers disappear  Mitosis is complete  A nuclear membrane forms around each set of chromosomes  The fibers disappear  Mitosis is complete

Cytokinesis  In eukaryotic cells that do not have a cell wall, division of the cytoplasm begins at the cell membrane  The cell membrane will eventually pinch all the way through the cell until there are two  In eukaryotic cells with a cell wall, a cell plate forms in the middle of the cell and becomes the new cell membranes that will separate the cell.  Once the cell is split a new cell wall forms  In eukaryotic cells that do not have a cell wall, division of the cytoplasm begins at the cell membrane  The cell membrane will eventually pinch all the way through the cell until there are two  In eukaryotic cells with a cell wall, a cell plate forms in the middle of the cell and becomes the new cell membranes that will separate the cell.  Once the cell is split a new cell wall forms

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