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B1 A) Cell Structures
B1 A) Cell Structures
All living organisms are made out of cells. There are two different types of cells, which are prokaryotic cells and eukaryotic cells. We will be looking at the differences between prokaryotic and eukaryotic cells towards the end of this section.
Eukaryotic Cells
Eukaryotic cells are more complex cells. The cells in animals and plants are eukaryotic.
Human & Animal Cells
Humans and animals are made from millions/ trillions of cells; there are around 30 trillion cells in an adult human. There are hundreds of different types of cells in humans and animals. The different types of cells have different structures that allows them to carry out their specific role (we will be looking at the structure of different types of cells in a later section). Despite these differences in the structure of cells, most human and animal cells contain the same components. An example of a typical human and animal cell is shown below:
Eukaryotic cells are more complex cells. The cells in animals and plants are eukaryotic.
Human & Animal Cells
Humans and animals are made from millions/ trillions of cells; there are around 30 trillion cells in an adult human. There are hundreds of different types of cells in humans and animals. The different types of cells have different structures that allows them to carry out their specific role (we will be looking at the structure of different types of cells in a later section). Despite these differences in the structure of cells, most human and animal cells contain the same components. An example of a typical human and animal cell is shown below:
Here is a summary of the different subcellular structures:
- Nucleus – contains the genetic material for the cell and controls the activities of the cell.
- Cytoplasm – a gel-like substance that makes up most of the cell. The cytoplasm is where the majority of reactions take place inside a cell. Enzymes are found in the cytoplasm of cells.
- Cell membrane – provides a boundary between the cytoplasm and the outside of the cell. The cell membrane controls what enters and leaves a cell.
- Mitochondria – where the majority of aerobic respiration reactions take place, which provides cells with the energy that they need. Mitochondria are sometimes referred to as the powerhouse of cells.
- Ribosomes – responsible for protein synthesis. An enzyme is an example of a protein that a ribosome would synthesise.
Plant Cells
Plant cells are also eukaryotic cells. An example of a typical plant cell is shown below.
Plant cells have all of the subcellular structures that a human/ animal cell has (nucleus, cytoplasm, cell membrane, mitochondria and ribosomes). They then have 3 additional subcellular structures which are:
- Rigid cell wall – found on the outside of the cell membrane. The cell wall strengthens the cell and supports the cell’s shape. The cell wall is made from cellulose, which is a carbohydrate.
- Chloroplasts – responsible for photosynthesis in plants, which allows plant cells to make food. Chloroplasts contain a pigment called chlorophyll, which makes plants green and helps the plant cells to absorb the sunlight needed for photosynthesis.
- Permanent vacuole – a large space in the centre of plant cells that contains cell sap (a weak solution of sugars, minerals and salts).
Prokaryotes – Bacteria Cells
Bacteria cells are prokaryotic cells. Bacteria cells are considerably smaller than plant and animal cells (eukaryotic cells). A diagram of a bacteria cell is shown below:
Bacteria cells are prokaryotic cells. Bacteria cells are considerably smaller than plant and animal cells (eukaryotic cells). A diagram of a bacteria cell is shown below:
Bacteria cells have a cytoplasm that is surrounded by a cell membrane and a cell wall (the cell wall is similar to the cell wall in a plant cell, but it is more flexible).
Bacteria cells don’t have a nucleus. Instead, their genetic information is found in a strand of DNA that can freely move around in the cytoplasm; this single strand of DNA is referred to as chromosomal DNA. Bacteria cells may also have additional small rings of DNA called plasmids (a bacteria cell may have many plasmids).
Bacteria cells have a flagellum, which is a hair like structure that rotates to allow the bacteria cell to move. The bacteria cell will want to move towards beneficial substances (like nutrients or oxygen) and away from harmful substances (like toxins).
Bacteria cells do not have mitochondria or chloroplasts.
Bacteria cells don’t have a nucleus. Instead, their genetic information is found in a strand of DNA that can freely move around in the cytoplasm; this single strand of DNA is referred to as chromosomal DNA. Bacteria cells may also have additional small rings of DNA called plasmids (a bacteria cell may have many plasmids).
Bacteria cells have a flagellum, which is a hair like structure that rotates to allow the bacteria cell to move. The bacteria cell will want to move towards beneficial substances (like nutrients or oxygen) and away from harmful substances (like toxins).
Bacteria cells do not have mitochondria or chloroplasts.
Prokaryotic & Eukaryotic Cells
Here is a quick summary of the differences between prokaryotic and eukaryotic cells.
Eukaryotic cells have genetic material enclosed in a nucleus. Examples of eukaryotic cells are plant and animal cells. Eukaryotic cells are larger and more complex than prokaryotic cells. Eukaryotes are organisms that are made up of many eukaryotic cells.
Prokaryotic cells have genetic material that is not enclosed in a nucleus; instead, the genetic material is a DNA loop that can freely move around the cytoplasm (chromosomal DNA) and plasmids (rings of DNA). Prokaryotes are single celled organisms.
Here is a quick summary of the differences between prokaryotic and eukaryotic cells.
Eukaryotic cells have genetic material enclosed in a nucleus. Examples of eukaryotic cells are plant and animal cells. Eukaryotic cells are larger and more complex than prokaryotic cells. Eukaryotes are organisms that are made up of many eukaryotic cells.
Prokaryotic cells have genetic material that is not enclosed in a nucleus; instead, the genetic material is a DNA loop that can freely move around the cytoplasm (chromosomal DNA) and plasmids (rings of DNA). Prokaryotes are single celled organisms.