Chapter 1.4 : Cell structure and function pt. 1 Flashcards
What can the electron microscope reveal that the light microscope cannot reveal well
Organelles
What does the electron microscope require the specimen to be observable
Dead
What are the two major category with cells and name a few examples for each
-
Prokaryotic
Eg. Bacteria, archaea, etc -
Eukaryotic
Eg. Protists, fungi, animals, plants, etc
What components of the cell do all cell category have
- Plasma membrane: selective barrier
- Cytosol: substance inside cytoplasm
- Cytoplasm: bounded by plasma membrane excluding nucleus
- Chromosomes
- Ribosomes: to make proteins
What do prokaryotic cells do not have but eukaryotic cells do
Organelles: membranes bounded structures
Where is located most of the DNA in both major cells category
Eukaryotes: in nucleus
Prokaryotes: in nucleoid region (not membrane enclosed)
What does the “selective barrier” part of the plasma membrane refers to
That it only allows the passage of oxygen, nutrients, waste for the entire cell
Explain why ratio of surface area to volume is important
Because as size increases, the volume grows proportionately more than the surface area. Thus, we are a multitude of cells, because otherwise our volume would be too big to sustain.
Explain the usage of microvilli
To increase the surface area
Why are ribosomes important
To carry out the instructions of making proteins from the DNA
Which organelle contains most genetic info
The nucleus
What other organelles contains genetic information except the main one
Chloroplasts and mitochondria have some too
True or false, the nucleus is enclosed by a nuclear envelope which has a single membrane
False, it has a double-membrane
What is the nuclear lamina made of
Net made of protein filaments, lines the nuclear side of envelope and it’s here for structural purpose
Where are the chromosomes in the cell, what are they and what do they do
- Found in nucleus
- Are long DNA double helixes with proteins
- Carry genetic information
What is chromatin composed of
DNA and proteins
How much chromosomes are in most human cells
46, 23 in sex cells
Where is the nucleolus located and what’s its purpose
- Inside the nucleus
- The site of rRNA synthesis
Describe what is direct physical continuity
When there’s a fusion/exchange of membranes, one becomes another, linked together
What does the endoplasmic reticulum consists of
Network of membrane tubules and sacs called cisternae
What is the ER membrane continuous with
The nuclear envelope
What differentiates the look between the smooth ER and the rough ER
The smooth er’s surface lacks ribosomes opposed to the rough er who is studded with ribosomes
What is the function of the smooth ER
- Synthesis of lipids
- Detoxification of drugs
- Storage of Ca^2+
- Metabolism of carbohydrates
What is the function of rough ER
- Protein secretion made by the ribosomes on its surface
- Polypeptide chain enters lumen as it grows from ribosome
- Has enzymes in membrane that make glycoproteins
- Its membrane keeps secretory proteins separate from those that will stay in cytosol
- Membrane factory cell
Name some cellular membranes that are part of the endomembrane system
- Nuclear envelope
- Endoplasmic reticulum
- Golgi apparatus
- Lysosomes
- Vesicles and vacuoles
- Plasma membrane
What are glycoproteins
Proteins with carbohydrates on it
What are the characteristics of ribosomes
- Made of rRNA and protein
- Carry out protein synthesis
- Not membrane bounded so not organelles
What role does the ribosome play in the process of proteins synthesis
It translates the mRNA into a polypeptide
What are the characteristics of Golgi apparatus
- Shipping and receiving centre
- Products of ER are modified, stored and sent to other places
- Very extensive in cells that secrete
- Can also makes some macromolecules
What products of ER are modified during transit through the Golgi
- Glycoproteins have carbohydrates modified
- Membrane phospholipids may also be altered
How are transport vesicles sorted and targeted in the Golgi
They receive molecular tags that direct them where they should go, external molecules that recognize the surface of the organelles where they should dock
What are lysosomes
- Membranous sac of hydrolytic enzymes that digest macromolecules
- Their enzymes work best in acidic environments
What is phagocytosis
Digestion of food: It describes the act of a unicellular eukaryotes feeding by engulfing smaller organisms or food particles
What are the variety of functions vacuoles can serve
- As food vacuoles
- Contractile vacuoles
- Central vacuole
What are the two organelles that transform energy
Mitochondria and chloroplasts
What do mitochondria produce from cellular respiration
ATP
What is the role of the chloroplast
To convert solar energy to chemical energy
How are the infoldings in the inner membrane of mitochondria are called
Cristae
Name the 2 inner compartments of the mitochondria
- intermembrane space
- mitochondrial matrix
Name the 3 components of the membrane system of chloroplasts
- Thylakoids : flattened interconnected sacs
- Granum : stack of thylakoids
- Stroma : fluid outside the thylakoids
Explain what is the endosymbiont theory
The theory suggests that an early ancestor of a eukaryotic cell engulfed an oxygen using, non photosynthetic prokaryotic cell which then became an endosymbiont (cell living within cell). Over time the two merged into one organism
Engulfing of oxygen using non photosynthetic prokaryotic cell —generations later—> Mitochondria
Engulfing of photosynthetic prokaryote –generations later—> Chloroplasts
What arguments support the endosymbiont theory
- Mitochondria and chloroplasts are bounded by 2 membranes just like the ancestral prokaryotes did
- Mito and chloro contain their own ribosomes and DNA
- Mito and chloro are “independent” (grow and reproduce inside cell on their own not outside)
What are the functions of peroxisomes
- carry out oxidative reactions using oxygen
- use oxygen to break down fatty acids
- in the liver: detoxify alcohol and poisons
What is the cytoskeleton
Network of fibres that extends thru the cytoplasm
What are the 3 types of molecular structures in cytoskeleton and what differentiates them
- Microtubules (thickest)
- Microfilaments (thinnest)
- Intermediate filaments
What are the main characteristics of microtubules
- Hollow rods
- Made from tubulin
- Responsible for the beating of flagella and cilia
- Move chromosomes
What are the main functions of microtubules
- Shape and support cell
- Resist compression (thickness)
- Serve as tracks for organelles with motor proteins
Where do microtubules grow from
The centrosome
What differentiates Flagellum and Cilium
- Flagellum has long appendage (1 or 2 per cell) formovement
- Cilium has short appendage, occur in large numbers and can act as an antenna
What are the main characteristics of microfilaments
- Thin solid rods
- Built from actin
- Occur in linear and structural networks
What are the function of microfilaments
- Bear tension, pulling forces
- Help support cell shape
- Used in the protein myosin in cell mobility and muscle contraction
- Amoebas used them to crawl (pseudopodia)
What are the main characteristics of intermediate filaments
- Made from keratin
- Bear tension
- Very sturdy and permanent
What are the main function of intermediate filaments
- Reinforce cell shape
- Fix position of certain organelles
- made from keratin
