The Cell Flashcards
Describe the importance of microscopy in the study of cellular biology
Microscopes are used to examine microorganisms in cellular biology and to study cells themselves and how they function in a living organism
Describe the role of cells in organisms
-Provide structure and support for the body
-Facilitate growth through mitosis
-Take in nutrients from food and convert those nutrients into energy
-Carry out specialized functions
-Contain the body’s hereditary material and can make copies of themselves.
Discuss the 3 principles of cell theory
Cell Theory:
-The cell is the basic unit of life
-All organisms are made of one or more cells
-All cells arise from pre-existing cells, “Omnis Cellula e Cellula”
Therefore, all cells today represent a continuous line of descent from the first living cells
Describe factors that limit cell size
-Most cells are relatively small due to reliance on diffusion of substances in and out of cells
-As the cell increases in size, its surface area-to-volume ratio decreases. (^2 vs ^3)
-The cell will either divide or die to minimize volume and maximize surface area.
-Cells must have a high surface area to volume ratio to maintain homeostasis
Rate of cellular diffusion affected by
-Surface area available
-Temperature
-Concentration gradient
-Distance
-Size of diffusing substance
Categorize structural and functional similarities in cells
-Protein synthesis
-Cytoplasm
-Ribosomes
-Plasma membrane (phospholipid bilayer)
Describe the organization of prokaryotic cells
-Circular DNA present in the nucleoid
-Ribosomes
-Cytosol
-Plasma membrane
-Cell wall: contains peptidoglycan
-Capsule: Mediates adherence of bacteria to particular surfaces. Capsules are known to protect bacteria from engulfment by predatory phagocytes and from attack by antimicrobial agents
-Fimbriae: extensions of the plasma membrane; involved in attachment to surfaces; major determinants of bacterial virulence because they allow cells to attach to tissues and to resist attack by phagocytic white blood cells
-Pilus: mainly function in gene transfer
-Flagellum
Describe eukaryotic cells
-Eukaryotic cells are bigger and more complex
-Possess a membrane bound nucleus
-Hallmark is cellular compartmentalization achieved through membrane bound organelles and the endomembrane system
-Genome consists of several linear chromosomes
Use the fluid mosaic model to describe the structure of the plasma membrane
A mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond.
Discuss the structure and function of the nucleus in eukaryotic cells
Structure:
-Nucleolus: region where rRNA synthesis takes place
-Chromatin: DNA plus associated proteins
-Nuclear envelope separates the nucleoplasm from the cytoplasm and has 2 phospholipid bilayers
-Nuclear pores control passage of materials in and out
Function:
The nucleus keeps eukaryotic DNA molecules organized and separated from cytoplasm. Therefore, it controls all cell activities.
Describe structure of ribosomes and their role in protein synthesis
Structure:
Ribosomes are catalytic and made up of a large subunit (top) and small subunit (bottom). Made of RNA and protein. They can be found in the cytooplasm or bound to the ER.
Function:
During protein synthesis, ribosomes assemble amino acids into proteins. Where protein synthesis occurs!!
Describe the structure and function of the chloroplast
Structure:
-Present in all cells of plants and some other eukaryotes
-Contain the green pigment chlorophyll
-2 membranes
-Thylakoids are membranous stacks that form grana
Function:
Photosynthesis
Also:
Mitochondria and chloroplast are complimentary. The products of respiration are the reactants of
photosynthesis and vice versa
Explain the probable origin of chloroplasts
Endosymbiotic Theory: Postulates that chloroplasts and mitochondria used to be prokaryotic cells that became trapped in evolving eukaryotic cells
Evidence:
-Mitochondria and ribosomes reminiscent of prokaryotic cells
-Divide by binary fission
-Size is similar to bacteria
-Contain plasmid DNA and ribosomes
Prokaryotes vs Eukaryotes
-No nucleus (circular DNA in nucleoid) vs nucleus
-0.1-10 micrometers vs 10-100 micrometers
-70S vs 80S
-Peptidoglycan vs cellulose walls
-Corkscrew flagellum powered by H+ gradient vs complex flagella
Describe the structure and function of the mitochondria
Structure:
-Bound by membranes: outer, inter membrane, inner membrane with cristae, and matrix.
-On the surface of the inner membrane and also embedded in it are proteins.
-Have their own DNA reminiscent of prokaryotic circular chromosomes (Endosymbiotic Theory).
Function:
-Cellular Respiration/ Factory of ATP
Eukaryotic organelles with membranes
-Nucleus
-ER
-Golgi body
-Vesicles
-Mitochondria
-Chloroplast
-Lysosome: intracellular digestion
-Peroxisome: inactivating toxins
-Vacuole: storage