Cells
Organism’s can be prokaryotes or eukaryotes
All living things are made of cells
Cells can be either prokaryotic or eukaryotic. Eukaryotic cells are complex and include
all animal and plant cells. Prokaryotic cells are smaller and simpler e.g. bacteria.
Plant and animal cells have similarities and differences.
The different parts of a cell are called subcellular structures
Nucleus - contains genetic material that controls the activities of the cell
Cytoplasm - gel-like substance where most of the chemical reactions
happen. It contains enzymes that control these chemical reactions
Cell membrane - holds the cell together and controls what goes in and out
Mitochondria - these are where most of the reactions for aerobic respiration
take place. Respiration transfers energy that the cell needs to work
Ribosomes - these are where proteins are made in the cell.
Plant Cells usually have all the bits that animal cells have, plus a few extra things that animal cells don’t have:
Rigid Cell Wall - made of Cellulose, it supports the cell and strengthens it
Permanent Vacuole - contains cell sap, a weak solution of sugar and salts
Chloroplasts - these are where photosynthesis occur they contain a green
substance called chlorophyll which absorbs the light needed for photosynthesis
Eukaryotic ( Plant Cell )
Bacteria are prokaryotes
Bacterial cells don’t have a true nucleus - instead they have a single
circular strand of DNA that floats freely in the cytoplasm
Prokaryotic Cell ( Bacteria Cell )
, Microscopy Cells are studied using microscopes
Microscopes is light and then this to form an image of a specimen and magnify
it. They lets us see individual cells and large sub cellular structures, like nuclei
Electron microscopes use electrons instead of light to form an image they
have a much higher magnification and resolution then light microscopes
Electron microscopes let us see much smaller things in more
detail like the internal structure of mitochondria and chloroplasts.
If you want to work out the image size or the real size of an
object you can rearrange the equation using this formula triangle.
image size
Magnification =
Image real size
Size
Magnification Real Size
Standard Form
Because microscopes can see such tiny objects sometimes it’s useful to write numbers in standard form
This is where you can change very big or small numbers with lots of zeros into something more manageable.
, Cell Differentiation
Cells differentiate to become Specialised
Differentiation is the process by which a cell changes to become specialised for its job
As cells change they develop different sub cellular structures and turn into
different types of cells, this allows them to carry out specific functions.
Most differentiation occurs as an organism develops.
The cells that differentiate in mature animals are mainly use for repairing and replacing cells
Some cells are on undifferentiated cells they are called Stem Cells.
Types of Specialised Cells
Sperm Cell - The function of a sperm is to get the male DNA to the female
DNA. It has a long tail and a streamlined head to help it swim to the egg.
Nerve Cell - The function of nerve cells is to carry electrical signals from one part of
the body to another. These cells are long and have branched connections at their ends.
Muscle Cell - The function of a muscle cells is to contract quickly. These cells are
long and contain lots of mitochondria to generate the energy needed for contraction.
Root Hair Cells – Root hair cells are specialised for absorbing water and minerals. They
grow into long hairs that stick out into the soil which gives the plant a big surface area.
Phloem - Transport substances such as food and water around plants. Phloem
cells have very few subcellular structures, so stuff can flow through them.
Xylem – Transport substances such as food and water
around plants. Xylem cells are hollow in the centre.
, Chromosomes and Mitosis
Chromosomes Contain Genetic Information
Most cells in your body have a nucleus which contains genetic material in the form of chromosomes
Chromosomes are coiled up lengths of DNA molecules which carries a large number of genes.
.
Different genes control the development of different characteristics e.g. Hair colour.
Body cells have two copies of each chromosome (one from the mother
and one from the father) 23 pairs of chromosomes in a human cell.
The Cell Cycle Makes New Cells for Growth, Development and Repair
Body cells in multicellular organisms divide to produce new cells as
part of a series of stages called the cell cycle.
The stage of the cell cycle when the cell divides is called mitosis which
is used to grow or replace cells that have been damaged.
The end of the cell cycle results in two new cells identical to the original cell
with the same number of chromosomes.
Before it divides, the cell has to grow and increase the amount
of subcellular structures such as mitochondria and ribosomes.
Growth and DNA Replication
Once its content and DNA has been copied the cell is ready for mitosis
The chromosomes line up at the centre of the cell and cell fibres pull
them apart and go to opposite ends of the cell.
It then duplicates its DNA so there’s one copy for each new cell. The DNA is copied and forms
X-shaped chromosomes. Each arm of the chromosome is an exact duplicate of the other.
Lastly the cytoplasm and cell membrane divide producing two new identical
daughter cells. The DNA is also identical to the parent cell.
Organism’s can be prokaryotes or eukaryotes
All living things are made of cells
Cells can be either prokaryotic or eukaryotic. Eukaryotic cells are complex and include
all animal and plant cells. Prokaryotic cells are smaller and simpler e.g. bacteria.
Plant and animal cells have similarities and differences.
The different parts of a cell are called subcellular structures
Nucleus - contains genetic material that controls the activities of the cell
Cytoplasm - gel-like substance where most of the chemical reactions
happen. It contains enzymes that control these chemical reactions
Cell membrane - holds the cell together and controls what goes in and out
Mitochondria - these are where most of the reactions for aerobic respiration
take place. Respiration transfers energy that the cell needs to work
Ribosomes - these are where proteins are made in the cell.
Plant Cells usually have all the bits that animal cells have, plus a few extra things that animal cells don’t have:
Rigid Cell Wall - made of Cellulose, it supports the cell and strengthens it
Permanent Vacuole - contains cell sap, a weak solution of sugar and salts
Chloroplasts - these are where photosynthesis occur they contain a green
substance called chlorophyll which absorbs the light needed for photosynthesis
Eukaryotic ( Plant Cell )
Bacteria are prokaryotes
Bacterial cells don’t have a true nucleus - instead they have a single
circular strand of DNA that floats freely in the cytoplasm
Prokaryotic Cell ( Bacteria Cell )
, Microscopy Cells are studied using microscopes
Microscopes is light and then this to form an image of a specimen and magnify
it. They lets us see individual cells and large sub cellular structures, like nuclei
Electron microscopes use electrons instead of light to form an image they
have a much higher magnification and resolution then light microscopes
Electron microscopes let us see much smaller things in more
detail like the internal structure of mitochondria and chloroplasts.
If you want to work out the image size or the real size of an
object you can rearrange the equation using this formula triangle.
image size
Magnification =
Image real size
Size
Magnification Real Size
Standard Form
Because microscopes can see such tiny objects sometimes it’s useful to write numbers in standard form
This is where you can change very big or small numbers with lots of zeros into something more manageable.
, Cell Differentiation
Cells differentiate to become Specialised
Differentiation is the process by which a cell changes to become specialised for its job
As cells change they develop different sub cellular structures and turn into
different types of cells, this allows them to carry out specific functions.
Most differentiation occurs as an organism develops.
The cells that differentiate in mature animals are mainly use for repairing and replacing cells
Some cells are on undifferentiated cells they are called Stem Cells.
Types of Specialised Cells
Sperm Cell - The function of a sperm is to get the male DNA to the female
DNA. It has a long tail and a streamlined head to help it swim to the egg.
Nerve Cell - The function of nerve cells is to carry electrical signals from one part of
the body to another. These cells are long and have branched connections at their ends.
Muscle Cell - The function of a muscle cells is to contract quickly. These cells are
long and contain lots of mitochondria to generate the energy needed for contraction.
Root Hair Cells – Root hair cells are specialised for absorbing water and minerals. They
grow into long hairs that stick out into the soil which gives the plant a big surface area.
Phloem - Transport substances such as food and water around plants. Phloem
cells have very few subcellular structures, so stuff can flow through them.
Xylem – Transport substances such as food and water
around plants. Xylem cells are hollow in the centre.
, Chromosomes and Mitosis
Chromosomes Contain Genetic Information
Most cells in your body have a nucleus which contains genetic material in the form of chromosomes
Chromosomes are coiled up lengths of DNA molecules which carries a large number of genes.
.
Different genes control the development of different characteristics e.g. Hair colour.
Body cells have two copies of each chromosome (one from the mother
and one from the father) 23 pairs of chromosomes in a human cell.
The Cell Cycle Makes New Cells for Growth, Development and Repair
Body cells in multicellular organisms divide to produce new cells as
part of a series of stages called the cell cycle.
The stage of the cell cycle when the cell divides is called mitosis which
is used to grow or replace cells that have been damaged.
The end of the cell cycle results in two new cells identical to the original cell
with the same number of chromosomes.
Before it divides, the cell has to grow and increase the amount
of subcellular structures such as mitochondria and ribosomes.
Growth and DNA Replication
Once its content and DNA has been copied the cell is ready for mitosis
The chromosomes line up at the centre of the cell and cell fibres pull
them apart and go to opposite ends of the cell.
It then duplicates its DNA so there’s one copy for each new cell. The DNA is copied and forms
X-shaped chromosomes. Each arm of the chromosome is an exact duplicate of the other.
Lastly the cytoplasm and cell membrane divide producing two new identical
daughter cells. The DNA is also identical to the parent cell.
