A1CC1 Chapter 2 - Cell Structure and Organisation Flashcards
What is an organelle?
A specialised structure found within eukaryotic cells that carries out a specific function for the cell.
What is a eukaryoic cell?
Eukaryotes contain DNA in chromosomes in a nucleus, and possess membrane bound organelles. Eg: Plants and Animals.
What is the resolving power?
The minimum distance by which two points must be separated in order for them to be seen as two distinct points rather than one focused image.
What is the nucleus and its function?
An organelle responsible for containing the DNA for protein synthesis.
What is the structure of the nucleus?
It has a double membrane for which the outer membrane is continuous with the endoplasmic reticulum. This double membrane contains pores to allow for mRNA to leave the nucleus.
What is the nucleoplasm?
This is a part of the nucleus which contains chromatin. The chromatin is what condenses to form chromosomes during cell division.
What is the nucleolus and its function?
A small spherical body found in the nucleus. It is responsible for the production of mRNA and ribosomes.
What is mitochondria?
The site of aerobic respiration, producing ATP.
Describe and explain the structure of mitochondria? (2)
- Inner membrane which folds into structures called cristae. These provide a large surface area for the attachment of enzymes (eg: ATP Synthase).
- Fluid Filled Matrix containing lipids and proteins, 70s ribosomes and a small loop of DNA.
What is a prokaryote?
A single celled organism lacking membrane-bound organelles, such as a nucleus, with its DNA free in the cytoplasm.
What are chloroplasts?
Found in photosynthetic plants. They are the site of photosynthesis.
Simply name all of the structures present in a chloroplast. (7)
- Double Membrane
- Loop of DNA
- Thylakoid membrane
- 70s Ribosomes.
- Starch grain
- Fluid Filled Stroma
- Intergranal Lamella/thylakoid.
What is the structure of chloroplasts? (3)
The organelle is surrounded by a double membrane which contains a fluid-filled stroma with starch grains, 70s ribosomes and a circle of DNA.
What is a thylakoid?
A structure located in the chloroplast; a granum is multiple thylakoids stacked together.
What is the endoplasmic reticulum?
A system of double membranes forming interconnected flattened fluid filled sacs called cisternae, which are connected to the nuclear envelope.
What is the role of the endoplasmic reticulum?
The transport of materials through the cell.
What is the difference between rough and smooth endoplasmic reticulum?
Rough endoplasmic reticulums have ribosomes attached to the outer surface and once proteins are synthesised there they are transported via the cisernae.
Smooth endoplasmic reticulums lack the ribosomes so instead are involved in the synthesis and transport of lipids.
What are ribosomes and their function?
Made up of rRNA and protein. Found in the cytoplasm. Their role is to assemble proteins during translation.
What is the structure of the ribosomes?
No membrane surrounding.
Consist of two subunits.
What does the small and large subunits of the ribosomes do?
The small subunit contains a mRNA attachment site.
The large subunit contains two tRNA attachment sites.
How do ribosomes differ between cells?
In eukaryotic cells there are the large 80s ribosomes.
In prokaryotic cells there are smaller 70s ribosomes.
What is the golgi body?
Similar to the endoplasmic reticulum, but more compact in shape. It is a stack of curved cisternae.
What is the function of the golgi body?
Vesicles containing polypeptides bud off the rough endoplasmic reticulum, and fuse with the golgi body for export.
What are lysosomes?
Small single membraned vacuoles that are pinched from the golgi apparatus containing the digestive enzyme lysozome.