Nucleus - Large Oval body near the centre of the cell. - The control centre for all activity. - Surrounded by a nuclear membrane.
Nucleoplasm - is the protoplasm in the nucleus. - contains genetic material ---> CHROMOSOMES (DNA)
Nucleolus - is found in the nucleus. - contains more genetic information (RNA)
Cell Membrane - the outer boundary of the cell. - it separates the cell from other cells. - it is porous ---> allows molecules to pass through.
Cell Wall ( Plant Cells Only ) - non living structure that surrounds the plant cell. - protects + supports the cell. - made up of a tough fibre called cellulose.
Cyto Plasm - cell material outside the nucleus but within the cell membrane. - clear thick fluid. - contains structures called organelles.
Vacuoles - are clear fluid sacs that act as storage areas for food, minerals, and waste. - in plant cell the vacuoles are large and mostly filled with water. This gives the plant support. - in animal cells the vacuoles are much smaller.
Mitochondria - power house of the cell. - centre of respiration of the cell. - they release energy for cell functions.
Chloro Plasts ( Plant cells only ) - contains a green pigment known as chlorophyll which is important for photosynthesis.
Ribosomes - tiny spherical bodies that help make proteins. - found in the cyto plasm or attached to the endo plasmic reticulum.
Endo Plasmic Reticulum ( ER ) - systems of membranes throughout the cyto plasm. - it connects the nuclear membrane to the cell membrane. - passageway for material moving though the cell.
Golgi Bodies - tube like structures that have tiny sacs at their ends. - they help package protein.
Lysosomes - " suicide sacs " - small structures that contain enzymes which are used in digestion. - if a lysosome were to burst it could destroy the cell.
Basic Cell Functions molecule transport *reproduction *energy conversion Cell Structures & Their Three Main Functions
The three main structures of the cell are the membrane, the cytosol and
its contents and the nucleus. The membrane is semi-permeable, allowing
selected nutrients and signal molecules inside. The cytosol holds a
variety of organelles, which perform specialized functions. The nucleus,
of course, holds the genetic code of the cell, along with the
nucleolus.
The Cell Membrane
The cell membrane encloses the cell. Its three main functions are to
provide a boundary around the cytoplasm, to bind the cells together and
to filter different chemicals to determine which are allowed to
penetrate the cell.
Molecules cross the membrane by active transport, diffusion and osmosis.
Carbohydrates in the membrane promote inter-cell adhesion. The lipid
molecules that make up most of the membrane are permeable to
water-soluble substances such as glucose, and fat-soluble elements such
as oxygen and carbon dioxide.
The Cytosol
The cytosol is the fluid between the cell membrane and the cell nucleus.
It is filled with specialized organelles. The three main functions
performed in the cytosol are protein synthesis, making energy from
nutrients available for other cells processes and signal transfer.
ATPand Protein
ATP is produced in the cytosol. It is the energy source used by the
chemical processes in the cell. It is produced by mitochondria, a type
of organelle in the cytosol numbering in the hundreds. Because of their
function, mitochondria are called the powerhouses of the cell.
Proteins are also produced in the cytosol. They are created in
ribosomes, ribbon-like organelles that reside on another organelle
called the endoplasmic reticulum.
Signal Transfer
Signal transfer, or signal transduction, occurs across the cytosol, from
the membrane of the cell to the nucleus. Signals from the
outside---hormones, for example---trigger a reaction through the cell
membrane, which releases a signal chemical on the inside of the cell.
This way, the hormone never has to enter the cell to do its job.
The Nucleus
The three main functions of the nucleus are to control gene expression,
mediate the replication of DNA upon cell division and maintain DNA
integrity. A fourth, equally important function performed within the
nucleus is the production of ribosomes within the nucleolus, the only
protein synthesis that occurs within the nucleus.
Different seasons occur at different times because of the tilt and the rotation of the earth. So while the northern hemisphere has winter, the southern hemisphere has summer
Explanation: Drugs that improve cognitive functions such as Adderall and Dexedrine are stimulants. They help people with attention deficit hyperactivity disorder (ADHD) to be more focused. This type of drugs shouldn't be available to people without this disorder because it has been discovered that people misuse it and it is associated with psychosis, myocardial infarction, cardiomyopathy, and even sudden death. So this type of drug should be only available when prescribed to someone with ADHD.
