Lecture Focus Questions; Cell Structure Flashcards
What are the 6 characteristics of life?
- Complexity & organization
- Responds to external environment
- Homeostasis
- Carries out metabolism & growth
- Reproduces & maintains heredity
- Adaptation to environment
What does Cell Theory state?
-It states that all living organisms are made of cells & that all cells (except first one) come from pre-existing cells
What do the cells from pre-existing cells describe?
-They describe reproduction, heredity, adaptation, & evolution
What is the range of the size of cells?
-It is a 1000-fold range from 1micrometer to 1 milimeter
Why can’t cells be too small?
-They won’t have enough essential materials
Why can’t cells be too big?
-They won’t have enough surface area to import materials & export waste
What are the 2 different basic cell architectures?
-Eukaryotic & prokaryotic cells
What is the difference between the architecture of Eukaryotic & Prokaryotic cells?
-Eukaryotic have distinct nucleus & a series of internal membranes while Prokaryotic cells do not
What domains of life do Prokaryotic cells include?
-Bacteria & Archea
What is the basic cell structure of Prokaryotic cells?
- They have cell walls of Peptidoglycan outside of a plasma membrane
- Inside the plasma membrane, there is a cytoplasm & loosely organized nucleoid that contains the DNA
- They also have ribosomes= site of protein synthesis
What do Prokaryotic cells NOT have?
-Membrane-bound organelles
What is the difference between the cell wall of a prokaryotic cell, a plant cell & fungi?
- Prokaryotic cells have a cell wall made of Peptidoglycan
- Plant cell walls are made of Cellulose
- Fungal cell walls are made of Chitin
What is Peptidoglycan made of?
-It is a combination of Carbohydrate polymers & short polypeptides
What is the basic architectural principle of Eukaryotic cells?
-Compartmentalization of membrane-bound organelles & specialization of their functions
What is the structure of the Nuclear Envelope?
- It consists of 2 membranes where each is a lipid bilayer
- The envelope is pierced by nuclear pores which provide a regulated pathway for material to travel between nucleus & cytoplasm
What structures does the Nucleus of Eukaryotic cells contain?
- Chromosomes
- Nucleolus
- Nuclear Lamina
- Nuclear Matrix
What is the function of Chromosomes?
-They are long linear molecules of DNA that contain genetic info
What 2 things are chromosomes combined with to make chromatin?
-RNA & proteins
What is the function of the Nucleolus?
-It is the site of rRNA transcription & ribosome formation
What is the structure of the Nuclear Lamina?
-It is a mesh of proteins lie immediately underneath the inner bilayer of the nuclear envelope
What is the structure of the Nuclear Matrix?
-It is a 2nd mesh of proteins that extends throughout the volume of the nucleus
What kind of covalent bond needs to make a protein?
-Amide bonds (peptide bonds when connecting to amino acids)
What are Ribosomes made of?
-rRNA & protein
What is the role of rRNA in a ribosome?
-They form the core of the ribosomes structure & is the actual catalytic molecule that speeds up the formation of amide/peptide bonds in the protein
What is the order of events in protein synthesis?
1) mRNA is transcribed in the nucleus
2) mRNA exits through nuclear pores
3) mRNA meets small subunits of the ribosome in the cytoplasm
4) mRNA & small subunit are joined by larger subunit
5) then mRNA is translated into protein
What is the sequence of amino acids in a protein determined by?
-It is determined by the sequence of the nucleotides in the mRNA
What are the subdivisions of the endomembrane system?
- Endoplasmic Reticulum
- Golgi complex
- Membrane-bound vesicles for transporting materials between parts of the system
What is the function of the Rough Endoplasmic Reticulum?
-It is the synthesis of proteins destined for the membrane, secretion, or other organelles
How are proteins synthesized?
- They are synthesized by ribosomes on the RER= segregates all the protein/ part of it inside the lumen of the RER after synthesis
- The proteins also undergo Glycosylation while in the lumen of the RER
What is the function of the Smooth Endoplasmic Reticulum?
- It is to synthesize the membrane components phospholipid & cholesterol
- And to detoxify foreign substances (drugs/ toxins)
What is the relationship between the Golgi & ER?
- They are both a system for synthesizing proteins & lipids & directing them to their correct location in the cell
- Protein & lipid material starts at ER & moves to the cis face of the Golgi via transport vesicles
What is the role of the Golgi?
-It further modifies proteins & sorts them by their eventual destinations
What is the pathway for protein secretion?
1) starts out in RER
2) then transport vesicle
3) enters cis face of Golgi
4) Exists the Golgi via trans face
5) gets into transport vesicle
6) Then fuses w/ plasma membrane & exists via Exocytosis
What is Endocytosis?
-It is the process of bringing bulk materials into the cell
What is Exocytosis?
-It is the process of letting bulk material out of the cell
What are the 3 different types of Endocytosis?
- Phagocytosis (cell eating)
- Pinocytosis (cell drinking)
- Receptor-Mediated endocytosis
What properties do Lysosomes have?
-They have an acidic pH & a set of digestive, hydrolytic enzymes
What is the role of Lysosomes in Endocytosis?
-They digest the material that is brought into the cell via endocytosis & convert it into material that is useable for the cell
What happens to the material from Endocytosis?
- It accumulates in endosomes
- And then a primary lysosome fuses w/ the endosome to generate a secondary lysosome & digest material inside the vesicle
What is the structure of the Mitochondrial Membranes?
- Mitochondria have 2 membranes
- The outer membrane covers the entire organelles
- The inner membrane is extensively folded= cristae
- The space inside the inner membrane= matrix while the space between the 2 membranes= intermembrane space
What were Mitochondria Originally?
-They were originally free-living bacteria that became incorporated into the cytoplasms of Eukaryotic cells
What do Mitochondria and Chloroplasts have in common?
- They were both free-living bacteria
- They also have multiple membranes
- And they both have DNA chromosomes that are remnants of DNA chromosomes that they had when they were free living
What organelles are unique to plants?
- Plastids (chloroplast)
- Vacuoles
- Cell wall made of cellulose
What is the membrane structure of a Chloroplast?
- They have 3 membranes
- The outer membrane completely covers the organelles
- The inner membrane also covers the organelle
- The thylakoid membrane is shaped into disks & is the site of photosynthesis
What are the 3 different cytoskeletal elements?
- Microfilaments
- Microtubules
- Intermmediate filaments
What are Microfilaments?
- They are made of chitin
- They are also long, thin fibers that support the cell
- they also use the motor protein Myosin to help w/ muscle contraction
What are Microtubules?
- They are made of tubulin
- They are hollow tubes that provide structural support & help w/ movement by serving as “railroad tracks” for Dynein & Kinesin
What are Intermediate Filaments?
- They are long strands made of fibrous protein subunits non-covalently bonded end to end
- They provide structural support in the cell (nuclear lamina) BUT DO NOT HAVE ROLE IN MOVEMENT
What motor proteins interact with Microtubules?
-Dynein & Kinesin
What motor proteins interact with Actin filaments (microfilaments)?
-Myosin
Where is the Extracellular Matrix found?
-It is found outside the cell
What is the Extracellular Matrix made of?
-It is made of proteins & carbohydrates
How is the Extracellular Matrix Synthesized?
-It is synthesized inside the cells & then secreted by cells & then holds the cells together into tissues
What is Fibrous connecting tissue?
-They contain a large amount of extracellular matrix w/ few cells
(includes ligaments & tendons)
What are Epithelial Cells?
- They are cells that form layers that often line the internal cavities of the body (intestine)
- They are also separated from the rest of the body via a sheet of extracellular matrix called the Basil Lamina (basement membrane)
