Topic 2.1 Cell Structure
Differentiation Process
1. Zygote
A fertilised cell contains all the information for it to grow into a human being with hundreds of specialised cell
types.
2. Specialisation
An egg divides to form a ball of identical cells. If these cells are separated at this time, it is still capable of
developing into a human being.
Tissue - Group of similar cells, which work together for a similar function.
Organ - A group of different tissues which work together for a common function.
System - A group of organs, working together, for an overall common function.
Skin is both an organ and tissue:
Skin as an organ: Skin as a system:
Muscle tissue Glands
Nervous tissue Receptors
Epithelial tissue
Connective tissue
Eukaryotic - Any cell with a nucleus.
Functions:
Microvilli:
Folded cell membrane - Increases SA.
, Nucleus :
- Surrounded by a double membrane called nuclear membrane - This membrane controls the passage of
material between the cytoplasm and the nucleus.
- The nuclear membrane is perforated by pores called nuclear pores, which allow the passage of large
molecules such as RNA, in and out of the nucleus.
- Within the nucleus is the nucleolus. This is the site of ribosomal RNA synthesis. Ribosomal subunits are
synthesised within the nucleus, but assembled outside of the nucleus.
- Separates the nucleus from the rest of the cell.
- Contains DNA
Mitochondria:
- Involved in ATP production during aerobic respiration
- Matrix contains proteins, lipids and some DNA.
Endoplasmic Reticulum:
- Joined the nuclear envelope.
- Helps move substances within cells
Rough Endoplasmic Reticulum:
- Site of protein synthesis (folding of protein)
Smooth Endoplasmic Reticulum:
- Site of carbohydrate and lipid production.
Ribosomes:
- They are the site of protein synthesis by joining amino acids.
- Has two subunits made up of protein and RNA
- The eukaryotic cell contains 80s ribosomes.
- Very small, only 25 nm in diameter.
Golgi Apparatus:
- Receives vesicles, labels with carbs.
- Sorts, modifies and packages macromolecules into vesicles, such as proteins and triglycerides.
Lysosome:
- Used to break down unwanted structures within the cell.
- Contain hydrolytic enzymes
- Involved in immune response and cell renewal.
- Digest pathogens - Phagocytosis.
Cell Surface Membrane:
- Made up of phospholipids, proteins, enzymes and carbohydrates arranged into what is described as a
fluid mosaic model.
- Controls the passage of molecules in and out of the cell.
Differentiation Process
1. Zygote
A fertilised cell contains all the information for it to grow into a human being with hundreds of specialised cell
types.
2. Specialisation
An egg divides to form a ball of identical cells. If these cells are separated at this time, it is still capable of
developing into a human being.
Tissue - Group of similar cells, which work together for a similar function.
Organ - A group of different tissues which work together for a common function.
System - A group of organs, working together, for an overall common function.
Skin is both an organ and tissue:
Skin as an organ: Skin as a system:
Muscle tissue Glands
Nervous tissue Receptors
Epithelial tissue
Connective tissue
Eukaryotic - Any cell with a nucleus.
Functions:
Microvilli:
Folded cell membrane - Increases SA.
, Nucleus :
- Surrounded by a double membrane called nuclear membrane - This membrane controls the passage of
material between the cytoplasm and the nucleus.
- The nuclear membrane is perforated by pores called nuclear pores, which allow the passage of large
molecules such as RNA, in and out of the nucleus.
- Within the nucleus is the nucleolus. This is the site of ribosomal RNA synthesis. Ribosomal subunits are
synthesised within the nucleus, but assembled outside of the nucleus.
- Separates the nucleus from the rest of the cell.
- Contains DNA
Mitochondria:
- Involved in ATP production during aerobic respiration
- Matrix contains proteins, lipids and some DNA.
Endoplasmic Reticulum:
- Joined the nuclear envelope.
- Helps move substances within cells
Rough Endoplasmic Reticulum:
- Site of protein synthesis (folding of protein)
Smooth Endoplasmic Reticulum:
- Site of carbohydrate and lipid production.
Ribosomes:
- They are the site of protein synthesis by joining amino acids.
- Has two subunits made up of protein and RNA
- The eukaryotic cell contains 80s ribosomes.
- Very small, only 25 nm in diameter.
Golgi Apparatus:
- Receives vesicles, labels with carbs.
- Sorts, modifies and packages macromolecules into vesicles, such as proteins and triglycerides.
Lysosome:
- Used to break down unwanted structures within the cell.
- Contain hydrolytic enzymes
- Involved in immune response and cell renewal.
- Digest pathogens - Phagocytosis.
Cell Surface Membrane:
- Made up of phospholipids, proteins, enzymes and carbohydrates arranged into what is described as a
fluid mosaic model.
- Controls the passage of molecules in and out of the cell.
