Topic 1 - Cell Structure Flashcards
Millimeters into Micrometers into Nanometers
1mm equal 1000μm, 1μm equals 1000Nm
Equation for Calculating actual size of a specimen
Actual Size = Image Size/Magnification
Define Magnification
The number of times an image is larger than the original
Define Resolution
The smallest distance between 2 points where both points can still be distinguished
What are the two types of microscopes?
Optical Microscopes (Light) and Electron Microscopes (SEM and TEM)
Which kind of microscope has better resolution and why?
Electron Microscopes due to a electron having a shorter wavelength compared to light
Structure of Nucleus:
Nucleus surrounded by nuclear envelope, a double membrane, nuclear pores enable movement of molecules into and out of nucleus. Genetic material is found within the nucleus. Nucleolus is a region within the nucleus that synthesizes ribosomes
Roles of nucleus
To store the genetic material (DNA) of the cell. To synthesize ribosomes. To regulate production of messenger RNA for protein synthesis.
What are the functions of the cell surface membrane
It encloses cell to form the boundary between the cytoplasm and the outside environment. To control the movement of substances in and out of the cell, as it is selectively permeable. Contains proteins and important molecules for cell signaling and recognition.
How does the structure of the rough endoplasmic reticulum (RER) relate to its function?
The RER contains ribosomes on its surface for the synthesis of proteins. The RER membranes spread extensively throughout the cell for the transport of proteins.
Difference between SER and RER
SER does not have ribosomes on the surface
What is the function of the smooth endoplasmic reticulum (SER)?
SER synthesizes and transports lipids
Structure of Mitochondria:
Oval-shaped. Double membrane bound, inner membrane folded into cristae. Contains jelly-like fluid called the matrix. Contains circular DNA and 70S ribosomes.
Roles of Mitochondria:
Aerobic respiration, which produces ATP. The ATP is used for energy-requiring processes.
Function of Golgi Body:
Modification and packaging of protein and lipids for exocytosis or distribution within the cell. It also produces lysosomes.
What are lysosomes?
Vesicles from the Golgi body that contain digestive enzymes e.g. proteases, lipases and lysozymes.
Function of lysosomes
They hydrolyze ingested pathogens in phagocytes. They digest old, worn out organelles in the cells. They break down cells after cell death.
What are the two types of ribosomes and where are they found?
80S ribosomes are found in eukaryotic cells - in the cytoplasm and on the RER. 70S ribosomes are found in prokaryotic cells, chloroplasts and mitochondria.
Structure of ribosomes:
Ribosomes contain two subunits. Each subunit is made up of a ribosomal RNA molecule and a protein.
Function of ribosomes:
Protein synthesis
Function of Centrioles and microtubules
Centrioles organize microtubules . Microtubules compose the cytoskeleton to give structure and allow transport within the cell.
What is Cilia?
Cilia is a hair-like structure that projects from a cell. Cilia may be able to move (motile) or be stationary (non-motile).
What is Microvilli?
Microvilli are small protrusions of the cell membrane.
How does microvilli aid in exchange of substances in cells?
The microvilli increase the surface area of a cell to increase the efficiency of exchange. For example, the epithelial cells of the intestines have microvilli to absorb the products of digestion.
Structure of Chloroplasts:
Chloroplasts have a double membrane and contain a fluid called stroma. Within the chloroplast, thylakoids are arranged into interconnected stacks of grana. They also contain 70S ribosomes and circular DNA.
Name the photosynthetic pigment in chloroplasts.
Chlorophyll
Function of Chloroplasts:
Photosynthesis, producing glucose, oxygen and some ATP
Functions of Cell wall
Protects cellular contents and gives rigidity to plant structure. It protects the cell from osmotic lysis. It can regulate the movement of water.
Function of Plasmodesmata
To allow the undisrupted flow of materials via the simplistic route, and the efficient exchange of substances between cells without having to cross the cell wall and membrane
What is the name of the membrane surrounding the large vacuole
The tonoplast
Function of vacuole
Acts as a temporary food store and helps maintain turgor pressure
Name the organelles and cell structures that are present in plant cells, but not in animal cells.
A cell wall, chloroplasts, large vacuole and tonoplast, plasmodesmata
Bacterial cells are what kinds of cells
Prokaryotic cells
Differences between Prokaryotic and Eukaryotic cells
Prokaryotic - Small, no membrane bound organelles, circular DNA, 70s ribosomes, no ER
Eukaryotic - Large, organelles may feature no membrane, single membrane or double membrane, true nucleus, 80s ribosomes, has ER
Key features of viruses
Viruses contain nucleic acids (either RNA or DNA) surrounded by a protein coat known as a capsid. The capsid can have attachment proteins to gain access to host cells. Viruses possess no organelles or ribosomes and so rely on host cells to synthesize the components of viral particles. Some viruses may have a phospholipid envelope surrounding the capsid e.g. HIV
