Intro To Cells Flashcards
What does cell theory state?
Cells are the fundamental units of life, all organisms are composed of cells, and all cells come from pre-existing cells.
What is the difference between unicellular and multicellular organisms?
Unicellular organisms consist of a single cell carrying out all functions of life, while multicellular organisms are composed of many specialized cells forming tissues and organs.
What is the central dogma of molecular biology?
DNA makes RNA makes protein.
Who first observed cells and when?
Robert Hooke in 1665.
What did Virchow assert in 1862 about cells?
Every cell stems from another cell.
What are prokaryotes characterized by?
No nucleus, DNA floats freely, no (or rudimentary) internal membranes, and a very basic cytoskeleton.
What distinguishes eukaryotic cells?
Presence of a nucleus containing DNA, complex internal membrane systems, and extensive cytoskeleton.
What are the two domains of prokaryotes?
Bacteria
Archaea = live in hostile environments such as acidic hot springs
What is the function of mitochondria?
Site of oxidative phosphorylation and ATP generation.
Can form complex dynamic networks in the cell
Has a double membrane —> inner membrane is extensively folded (forming Cristae) to increase surface area for cellular respiration
What is the role of the endoplasmic reticulum (ER)?
- Synthesis of secretory and membrane proteins, and lipids
- Entry point to secretory pathway
- Network of interconnected spaces enclosed by a single membrane that is continuous with the nuclear envelope
What is the function of the Golgi apparatus?
- Processing and packaging proteins and lipids received from the ER in form of vesicles
- Cargo transits Golgi to the plasma membrane
- Modifies cargo e.g. glycosylation
- Sorting of cargo to correct location
Fill in the blank: The cytosol is the site of ______.
protein synthesis (of non membrane proteins) and degradation, intermediary metabolism and the location of the cytoskeleton
What are the components of the cytoskeleton?
Actin filaments, microtubules, intermediate filaments.
Name a model organism used for studying prokaryotes.
E. coli.
What is the significance of ATP and GTP in cellular functions?
They play key roles in energy transfer and regulation of protein activity.
What does phosphorylation do?
Phosphate group is added to OH bond
It controls protein function, influencing cell cycle, growth, metabolism, gene expression, division, and survival.
True or False: Eukaryotic cells lack a cytoskeleton.
False.
What is the primary role of the nucleolus?
Ribosomal RNA synthesis and ribosome assembly.
What is the purpose of the cytoplasm?
Everything inside plasma membrane but outside the nucleus, including organelles.
What type of proteins are synthesized in the rough ER?
Secretory and membrane proteins.
What is the role of smooth ER?
Active in lipid metabolism and in the liver for detoxification of lipid-soluble compounds.
Has no ribosomes
Fill in the blank: The ___________ is involved in the modification and sorting of cargo proteins.
Golgi apparatus.
What is the function of the sarcoplasmic reticulum?
ER derived calcium store in muscle cells, crucial for muscle contraction.
What is a key feature of the mitochondrial inner membrane?
It is extensively folded, increasing surface area for cellular respiration.
What are model organisms used for?
To study biological mechanisms.
Structure of the nucleus
- Contains DNA as chromosomes
- Surrounded by a nuclear envelope = double membrane
- Nucleolus = where ribosomal RNA and ribosomes are assembled
What are organelles?
- surrounded by one or more membranes made up of lipid bilayers that form a physical barrier from the Cytosol
- allow different protein contents and chemical environments to be maintained
- allows each organelle to have a specialised function
Structure of the Cytosol
Soluble, aqueous fraction
Very crowded
Key roles of ATP and GTP
- nucleotide binding can control protein shape, activity and function
- fast hydrolysis of ATP drives movement
- slow hydrolysis rate gives a switch activity (turns protein on/off) —> on when GTP is bound
- involved in phosphorylation = addition of phosphate group from ATP to serine, threosine or tyrosine controls protein function
Post-translational modifications of amino acids
Common amino acids are grouped according to whether their side chains are
- acidic
- basic
- uncharged polar
- nonpolar
Involved in N-glycosylation (in the ER), O-glycosylation and phosphorylation
