3.4 Eukaryotic Cell structure Flashcards
What is meant by the ultrastructure of a cell
The specific internal structure of a cell that makes it suited for its job
What is the function of the nucleus
- Act as a control centre of the cell through the production of mRNA and tRNA and hence protein synthesis
- Retain the genetic material of the cell in the form of DNA
- Manufacture ribosomal RNA and Ribosomes.
What is the function of the nucelus’ nuclear envelope
It is a double membrane that surrounds the nucleus. Its outer layer is continuous with the ER of the cell and has ribosomes on its surface.
It controls the entry and exit of materials in and out of the nucleus
What is the function of the nucleus’ nuclear pores
They allow the passage of large molecules, like mRNA.
What is the function of the nucleoplasm inside the nucleus
It is a jelly-like granular material that makes up the bulk of the nucleus
What is the function of chromosomes
To consist of protein-bound, linear DNA
What is the function of nucleolus’ in the nucleus
To manufacture ribosomal RNA and assemble the ribosomes. There may be more than one
What is the function of mitochondrias
To act as the site of the aerobic stages of respiration
What is the function of a mitochondrias double membrane
To control the entry and exit of materials. The inner of the two membranes form extensions known as cristae
What is the function of mitochondrial cristae
To provide a large surface area for the attachment of enzymes and other proteins involved in respiration. They are extensions of the inner-membrane
What is the function of the mitochondrial matrix
They make up the rest of the mitochondria. They contain protein, lipids, ribosomes and DNA that allow the mitochondria to control the production of some of their own proteins
What is the function of chloroplasts
To act as the site of photosynthesis
What is the chloroplast envelope
A double plasma membrane that surrounds the organelle. It controls what enters and leaves the chloroplasts
What is the grana of the chloroplast
Stacks of thylakoids. Inside a thylakoid is the photosynthetic pigment chlorophyll
What is the stroma of the chloroplast
A fluid-filled matrix where the second stage of photosynthesis takes place.
How are chloroplasts adapted to their function of harvesting sunlight
- The granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis.
- The fluid of the stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis
- Chloroplasts contain both DNA and ribosomes so they can quickly make the required proteins for photosynthesis
What is the endoplasmic reticulum
A sheet of membranes that are continuous with the outer nuclear membrane.
What is the rough endoplasmic reticulum
A sheet of membranes with ribosomes embedded in it.
What are the functions of the RER
- Provide a large surface area for protein synthesis and glycoproteins
- Produce a pathway for the transport of materials, especially proteins, throughout the cell
What are the functions of the SER
- Synthesise, store and transport lipids
2. Synthesise, store and transport carbohydrates
What are the functions of the golgi apparatus
- Add carbs to proteins to form glycoproteins
- Produce secretory enzymes, such as those secreted by the pancreas
- Secrete carbs, such as those in making cell walls in plants
- Transport, modify, and store lipids
- Form lysosomes
Where are golgi apparatuses specifically well developed
In secretory cells, like epithelial cells that line the intestines.
What are the functions of lysosomes
- Hydrolyse material ingested by phagocytic cells, like white blood cells and bacteria
- Release enzymes to the outside of the cell in order to destroy material around the cell
- Digest worn out organelles so that the useful chemicals they are made of can be re-used
- Completely break down cells after they have died (autolysis)
Where are lysosomes abundant
Secretory cells, like epithelial cells and phagocytic cells
What are the two types of ribosomes
80s ribosomes - eukaryotic cells
70s ribosomes - prokaryotic cells
What are ribosomes made up of
Ribosomal RNA and protein
What is the function of ribosomes
Protein Synthesis
What does a cell wall consist of
Microfibrils of cellulose
What is the function of cell walls
- To provide mechanical strength in order to prevent the cell bursting under osmotic gain or loss
- To give mechanical strength overall
- To allow water to pass along it and contribute to the movement of water within the plant
What are the cell walls of algae made up of
Cellulose or glycoproteins
What are the cell walls of fungi made up of
Chitin, glycan and glycoproteins
What is a vacuole
A fluid-filled sac bounded by a single membrane called a tonoplast
What are the components present in the vacuoles solution
Mineral salts, sugars, amino acids, wastes and pigments such as anthocyanins
