Cells And Subcellular Structures Flashcards
What is the cell theory?
All living organisms are made up of one or more cells, the cell is the basic unit of life, cells arise from existing cells by division.
What are the two main types of cells?
- Prokaryotes
- Eukaryotes
Define prokaryotes.
No nucleus, always single-cellular.
Define eukaryotes.
Have a nucleus, can be single or multicellular.
List the types of eukaryotic organisms.
- Animals
- Plants
- Fungi
- Protozoans
What is the evolutionary origin of cells?
Ancestral prokaryotes evolved into bacteria, anaerobic ancestral eukaryotes, and archaea over billions of years.
What is the structure of the cell (plasma) membrane?
Bilayer of phospholipids, cholesterol, and embedded transmembrane proteins with lipid rafts.
What are phospholipids?
Amphipathic molecules with a hydrophilic phosphate group and hydrophobic lipid tails.
What are the main roles of the cell membrane?
- Barrier
- Communication
- Import and export
- Electrical capacitor
What is the cytoskeleton?
A network of protein fibers.
List the components of the cytoskeleton.
- Actin filaments
- Intermediate filaments
- Microtubules
What are the main roles of the cytoskeleton?
- Maintenance of shape and stability
- Adaptation of shape to change
- Cell division
- Motility
- Movement of particles within cells
What does the cytoplasm (cytosol) contain?
Aqueous solution of defined pH (7.2) and ion composition, high concentration of proteins (20-30% metabolic enzymes, messengers).
What surrounds the nucleus?
Two lipid double layers.
What is chromosomal DNA?
DNA packed with histones and gene regulatory proteins.
What is the nucleolus?
Site of ribosome synthesis and can capture gene regulatory proteins.
What is the function of the rough endoplasmic reticulum (RER)?
Synthesis of secreted and transmembrane proteins.
What is the function of the smooth endoplasmic reticulum (SER)?
- Synthesis of lipids and steroid hormones
- Detoxification
- Release of glucose from the liver
What are mitochondria?
Double membrane organelles folded into cristae.
What processes occur in the mitochondria?
- Oxidative phosphorylation
- Citric acid (Krebs) cycle
- Heat production
- Ca2+ storage
- Programmed cell death (apoptosis)
What are lysosomes?
Membrane-bound organelles in animal cells that degrade unwanted proteins, membranes, and organelles.
What is the optimal pH for lysosomal enzymes?
pH 4.8-5.
What are peroxisomes?
Organelles involved in fatty acid oxidation that produces hydrogen peroxide.
What enzyme neutralizes hydrogen peroxide in peroxisomes?
Catalase.
Fill in the blank: The cytosol has a defined pH of _______.
7.2
True or False: Eukaryotic cells always have a nucleus.
True
What is the content of lysosomes?
Acidic
