Studying cells Flashcards
What is the structure of nucleus in eukaryotic cells? (3)
Largest organelle in the cell
Double membrane called the nuclear membrane/envelope
Nuclear pores which allows the passage of molecules such as mRNA, in and out of the nucleus
What is the function of nucleus in eukaryotic cells? (4)
Contains DNA
The nucleolus is responsible for making ribosomal RNA and ribosomes
Ribosomal proteins are synthesised within the nucleus but assembles outside the nucleus
Contains chromatic (DNA coiled around proteins called histones)
What is the structure of mitochondria in eukaryotic cells? (3)
Have a double membrane
Inner membrane is highly folded to form cristae to increase surface area for attachment of ATP synthase enzymes
Within the inner membrane, the matrix contains proteins, lipids, mitochondrial DNA and ribosomes
What is the structure and function of rough endoplasmic reticulum in eukaryotic cells? (4)
Made from highly folded membranes with 80s ribosomes embedded
Membrane is folded into flattened sacks called cisternae
RER is joined to the nucleus (easier for mRNA to get there to make proteins)
RER synthesises and transports proteins throughout the cell
What is the function of smooth endoplasmic reticulum in eukaryotic cells? (1)
Recombines glycerol and fatty acid to make triglycerides
What is the structure and function of ribosomes in eukaryotic cells? (3)
Made up of 2 rRNA protein subunits
Two subunits of a ribosomes are made of a combination of long strands of rRNA, dotted with ribosomal proteins
Site of protein synthesis
What is the structure and function of Golgi apparatus in eukaryotic cells? (2)
Composed of flattened sacs made of membranes
Sacs are fluid filled and pinch off smaller sacs (called vesicles) at their ends
Sorts, modifies and packages molecules, such as proteins and triglycerides into vesicles
What is the structure of lysosomes in eukaryotic cells? (2)
Bound by a single membrane and have no internal structure
What is the function of lysosomes in eukaryotic cells? (2)
Used to hydrolyse damaged and worn-out organelles
Contain hydrolytic enzymes which are lysozymes in an acid solution, which must be kept separate from the rest of cell contents prevent them from digesting organelles
What is the structure and function of cell surface membrane in eukaryotic cells? (2)
Made up of phospholipids, specific transport proteins and carbohydrates arranged into a fluid mosaic model
Controls the passage of molecules in and out of the cell
What is the function of microvilli in eukaryotic cells? (3)
Finger like projections of the cell membrane which greatly increases the surface area of the cell surface membrane, this speeds up absorption of digested food.
Found on epithelial cells in the small intestines
What is the function of centrioles in eukaryotic cells? (2)
In mitosis, they form a network of spindle fibres across the cell onto which chromosomes attach
These fibres pull the chromosomes/chromatids apart during mitosis
Describe the structure of viruses (4)
Contain DNA or RNA
Surrounded by capsid (protein coat)
Has attachment proteins which enable it to bind to host cells
Has enzymes that it uses to replicate its genetic information and insert it into the host cell DNA
Name 2 structures found within a eukaryotic cell that cannot be identified using an optical microscope (2)
Mitochondria
Ribosome
Endoplasmic reticulum
Lysosome
Cell surface membrane
Describe the principles and the limitations of using a transmission electron microscope to investigate cell structure (5)
PRINCIPLES:
Electrons pass through very thin specimen
Denser parts absorb more electrons
So denser parts appear darker
Electrons have short wavelength so give a high resolution
LIMITATIONS:
Cannot look at living material/must be in a vacuum
Specimen must be very thin
Artefacts present
Complex staining method/long preparation time