Cell Structure and Function

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Cell Structureand Function

• Chapter 2

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What do cells do?

• Plant cells and Animal cells
• A single cell is the smallest structure that
  carries out the activities necessary for life. A
  cell is like a tiny factory. Different parts of
  the factory produce or control different things.
  One part gets food or water. Another part keeps
  the cell clean. Still other parts are in charge
  of reproducing. All parts of the cell must work
  together to run smoothly. An organism cannot
  survive without cells doing their work.

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• Animal and plant cells may look different but
  they share many similar features. They have at
  least 3 features in common cell membranes, a
  nucleus and cytoplasm. Look at txt. Pg. A47
• The cell membrane is the outer covering of the
  cell. Water and food enter through the cell
  membrane, and wastes leave through it. Plant
  cells have an additional structure called the
  cell wall which gives them extra support.

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• Each animal cell and plant cell contains a
  nucleus. The nucleus is the control center for
  the cell. It carries information for
  reproduction and directs all cell activities.
• The cytoplasm is a gel-like material that
  surrounds all parts of the cell within the
  membrane, including the nucleus and the
  organelles.

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• Organelles are small structures, each of which
  has a specific job.

Cell structure Function
Mitochondria Provide energy
Vacuoles Store materials
Nucleus Cell control center reproduction
Cell membrane Structure and transport
Golgi Bodies Endoplasmic Reticulum transport
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• The nucleus is the cells control center and
  acts during reproduction. The cell membrane
  gives the cell structure and transports materials
  into and out of the cell. The Golgi Bodies and
  Endplasmic Reticulum transport materials with the
  cell.

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Cell transportation

• A cell membrane is a special kind of barrier.
  It holds important cell materials inside it, but
  allows water, gases, and wastes to pass through.
• In passive transport, materials move into or
  out of the cell without the cell using any
  energy. The simplest kind of passive transport
  is diffusion.

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• Substances diffuse from regions of high
  concentration to regions of low concentration.
• Sometimes a cell needs to move materials
  opposite the way diffusion would move them. In
  active transport, substances move from regions of
  low to high concentration. This requires the
  cell to use its own energy.
• Sometimes large proteins in the cell membrane
  help move materials in and out. The proteins act
  as tunnels to allow only certain materials to
  pass.

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Using Energy

• All living things need energy to survive.
  Plants use a process called photosynthesis to
  make food by harnessing the energy from sunlight.
  This process takes place in chloroplasts, and
  depends on the green pigment chlorophyll.

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• During photosynthesis, water from the ground is
  combined with carbon dioxide from the air.
  Oxygen is produced and released into the air. A
  molecule of glucose is also produced. Glucose is
  one of the high energy compounds called sugars.
• All plants and animals depend on the sugars
  made by the plants for their food. They get
  energy from the sugars by the process of cellular
  respiration.

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• All plants and animals depend on the sugars
  made by the plants for their food. They get
  energy from the sugars by the process of cellular
  respiration.
• Mitochondria perform cell respiration, the
  reverse process of photosynthesis. This process
  combines oxygen from the air with glucose from
  food to form water and carbon dioxide. A lot of
  energy is released in the process

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• Mitochondria store this energy in a molecule
  called ATP. This molecule acts like a battery.
  The cell tap into ATP whenever it needs to use
  energy.

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Cell Division

• New organisms usually begin when cells from two
  parents combine to form a new cell. Soon the
  single cell divides to form two cells. The two
  divide to form four, and the four divide into
  eight cells. Millions of divisions occur as the
  cells become a complete organism.

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• As cells divide, they differentiate, which
  means they become different from one another.
  Early on the cells organize themselves into three
  groups, called germ layers. One layer will form
  the skin and nerves. Another layer becomes the
  lining of the digestive tract. The third layer
  becomes all the other body parts

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• Bacteria and other single-celled organisms can
  also copy themselves. This copying results in
  new individuals. When conditions favor division,
  a bacterial colony can double very quickly.

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Lesson 2 Specialized Cells

• Different cells for different Job
• All multicellular organisms have specialized
  cells that work together. Both plants and
  animals have tissues that perform specific jobs.
  Most complex organisms have a variety of tissues.

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• Epithelial tissues are sheets of cells that
  cover surfaces. They also line certain body
  cavities and blood vessels.
• Connective tissue, as the name implies, joins
  other tissues together. It also stores fat and
  make of specialized cells and fibers that stick
  to living cells. Bone is a type of connective
  tissue too.

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• All muscle tissue creates movement in one
  direction only, either by getting longer or
  shorter.
• Electrical impulses that constantly run through
  your body are produced and routed by nervous
  tissue.

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• Organs are made up of several tissue types that
  work together to perform one or more functions.
• The brain, heart, and liver are three human
  organs. Some organs, like kidneys, perform more
  than one function. Kidneys remove waste from the
  body and also help control blood pressure.

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Organ Systems

• The more complex the organism, the greater the
  number of organ systems that are needed to carry
  out life processes. Humans have 11 organ
  systems. The systems also influence one another.
  Some organs work for more than organ system.

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Urinary System

• This system helps regulate the amount of water
  and salt in the blood, as well as removing liquid
  wastes.

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Musculoskeletal system

• Supports all parts of your body and allows you
  to move different parts of your body. Bones
  anchor other body parts and provide the structure
  needed for movement
• Contracting your muscles makes your body parts
  move. The muscles also generate warmth for your
  body.

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Nervous System

• Your brain is an indispensable organ, the
  headquarters of the nervous system. All your
  senses feed information into the brain. The
  brain processes and responds to this information,
  often responding by sending signals down nerves
  to muscles. The brain also controls the other
  organ systems. Look at txt. Pg. A57

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• Four of the remaining organ systems help your
  body fight infection, and allow you to eat,
  breathe, and reproduce. Another system produces
  hormones that regulate many body functions.

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Endocrine System

• Your bodys endocrine system works like a
  chemical messenger system. The glands of the
  endocrine system act as a communication centers.
  Endocrine glands are a specialized group of cells
  that make and send out hormones. Hormones act as
  messages. They travel through the blood stream
  and are picked up only by certain cells.

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• Humans use about 50 different hormones. Some
  help regulate growth and energy use. Others
  control blood sugar, minerals, and other
  chemicals. Some hormones cause specific changes
  in the body.
• Many plants use hormones, too. These may cause a
  stem to bend toward the light, or could direct a
  plant to grow taller instead of wider.

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Gland Function
Pituitary Gland This gland in the brain makes at least 8 different hormones. Many control other glands.
Thyroid gland This helps regulate the bodys use of energy.
Thymus This gland helps the bodys immune system.
Adrenal Glands These manufacture hormones that regulate glucose respond to stress. They also influence reproductive hormones.
Pancreas This produces insulin and other hormones that affect the level of blood sugar. Lack of insulin leads to a disease called diabetes.
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Lesson 3How does disease affect cells?

• Cells and Diseases

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Causes of Diseases

• Many things can cause illness or disease. Some
  diseases result when the body is invaded by alien
  organisms or viruses. Other diseases result when
  body systems do not function properly.

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Infectious Diseases

• Infectious diseases are caused by harmful
  organisms or viruses. Bacteria some types of
  fungi are common types of infections. Certain
  types of worms can lodge in the intestines or
  muscles, causing several serious diseases.
  Protozoa carried by mosquitoes cause malaria.

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• Contagious diseases can be spread easily from one
  person to another. Other diseases, like those
  from food poisoning, are not contagious.
• Viruses are not living organisms because they are
  not made of cells. Viruses are common causes of
  infectious disease. Viruses contain generic
  instructions that take over a cells normal
  instructions. Typically, the virus instructs the
  cell to male more viruses.
• Many viral diseases are mild, like colds, the
  flu, chicken pox. Other viruses are more
  dangerous or even deadly. Viral diseases such as
  hepatitis or AIDS have killed many people.

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Non-infectious Diseases

• Non-infectious diseases occur when a body system
  does not function properly. These types of
  diseases cannot spread from person to person.
  Sometimes the diseases are caused by a condition
  that is inherited.
• Other times the diseases appears as a persons
  body ages. Healthy lifestyles and habits can
  help prevent many of these later-in-life diseases.

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• Poor nutrition causes many non-infectious
  diseases. People who do not receive the proper
  vitamins in their food can suffer a variety of
  illnesses and impaired organ functions.

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Fighting Disease

• Your body has 3 main lines of defense against
  invasion by disease agents. The first line of
  defense is made up of your bodys physical and
  chemical barriers. These include your skin,
  tears, salvia, earwax, and mucus.
• Your bodys second line of defense consists of
  processes that kick in should harmful agents
  enter.

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• One of these defenses is inflammation. The blood
  releases fluid and other products that enlarge
  the area and make it red and sore.
• The second line of defense can include the
  production of special cells called phagocytes.
  These cells surround and consume harmful disease
  agents that invade your body. Phagocytes are one
  type of white blood cells.

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• The body has a very powerful defense weapon to
  fight specific harmful agents of disease. Its
  called the immune system. And is your bodys 3rd
  line of defense.

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Immune System

• The immune system uses special cells that travel
  throughout the body recognize invading
  pathogens. These cells can recognize harmful
  invaders because they have surface structures
  different from those of normal body cells.
• Certain types of white blood cells produce
  special proteins called antibodies that also
  fight invaders.

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• After the body destroys invaders, the body begins
  to recover from illness. As an added benefit,
  some of the immune systems special white blood
  cells remain in the body. If the same pathogens
  invade the body again, these cells can
  immediately produce the needed antibodies. This
  means that the body is now immune to, or
  protected from that particular illness.

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Disease Prevention or Treatment

• Many diseases that were once deadly are now under
  control. Fro example, smallpox killed hundreds
  of millions throughout history. Yet in 1980, the
  World Health Organization declared smallpox to be
  eradicated, meaning it was wiped out.
• A vaccine usually contains an inactive version of
  a pathogen. When the body is exposed to the
  vaccine, it slowly makes antibodies against it.
  Later, should the real pathogen enter the body,
  the antibodies are ready right away to stop it.

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• Penicillin is an antibiotic that works by
  weakening the cell walls of bacteria, allowing
  water from outside to rush inside.