Unit 4: Cells Flashcards
Organelle function: Cell membrane/plasma membrane
Surrounds the cell; Keeps stuff in and out
Organelle function: Cytoplasm
Internal cell fluid which holds all other structures inside the cell
What are cell membranes composed of?
Phospholipids
What are phospholipids comprised of?
Hydrophilic head: Glycerol + Phosphate
Hydrophobic tails: 2 fatty acids (one saturated, one unsaturated)
What’s the polarity of the phosphate head?
Polar covalent bonds.
Hydrophilic
What’s the polarity of the fatty acid tails?
Nonpolar
Hydrophobic
What’s the organization of the phospholipid bilayer?
Head – Tails – Tails – Head
Do phospholipids interact with one another in the bilayer?
There are no chemical bonds between individual phospholipids.
A very flexible and fluid mosaic
Allows for movement of membrane and proteins embedded in the membrane
In what way does the cell membrane allow transport?
Selective permeability
The hydrophobic interior (brought to us by the hydrophobic fatty tails) prevents the transport of most molecules
It allows lipids and other small nonpolar molecules (such as O2) and very small polar molecules (such as H2O)
What are the two structure types of proteins that are contained in the cell membrane?
Integral and Peripheral
Integral proteins stick out on either end (span the entire membrane)
Peripheral proteins just stick out on one end
What’s the function of this protein: Receptors
Outside substances bind to them
What’s the function of this protein: Enzymes
Speed up the chemical reactions on the inside of outside of the cell
What’s the function of this protein: Aquaporins
Move water inside or outside the cell
What’s the function of this protein: Channels
Move other substances inside or outside the cell
What is cytoplasm comprised of?
Cytosol: water, ions, enzymes
Organelles
Organelle function: Nucleus
Holds the DNA
Houses the nucleolus
Bound by a double membrane nuclear envelope
Has nuclear pores to allow transport of particular molecules in/out
What is the nucleolus?
Where ribosomes are made and RNA is transcribed
What is chromatin?
A complex of DNA and proteins that forms the chromosomes within the nucleus
Exists in two forms: Euchromatin (less condensed) and Heterochromatin (condensed)
What are ribosomes?
Made of RNA and protein- rRNA
Make proteins using the info from RNA
Organelle function: Mitochondria
Contains its own DNA and ribosomes
Site of cellular respiration
What is cellular respiration?
The process of breaking glucose down to get energy
Organelle function: Peroxisomes
Breaks down toxic molecules
Organelle function: Vesicles
How proteins and other chemicals move around a cell
A membrane bubble
Travels using the endomembrane system:
- Smooth/rough ER
-Golgi apparatus
Organelle function: Smooth Endoplasmic reticulum (ER)
Houses enzymes to break down drugs and poisons; synthesizes lipids
Further away from the “maze”
Organelle function: Rough Endoplasmic reticulum (ER)
Helps with protein synthesis, folding, and sorting
Has ribosomes on its surface (making it appear “rough”)
Organelle function: Golgi apparatus
Assists with protein folding and modification
Repackages proteins into vesicles and sends them towards the cell membrane
What are lysosomes?
The digestive system of the cell, breaks down molecules for parts
Cytoskeleton composition from smallest to largest:
Microfilaments –> Intermediate filaments –> microtubules
These are all involved in cell structure and molecule movement within the cell
Microtubules?
Used as a scaffolding during cell growth/division
Microfilaments?
Strengthen and change the shape of a cell
Intermediate filaments?
Main framework of cells
What organelles organize the microtubules?
Centrosomes made up of 2 centrioles
Which cellular extensions are on the inside versus outside of the cell?
Microvilli, cilia, flagella
Microvilli are finger-like projections on the inside of the cell membrane to increase surface area
Cilia and flagella are on the outside of the cell
What are cilia?
Short and fringe-like
Has coordinated movements like a wave to move particles in a certain direction
What’s an example of cilia?
Cells lining the trachea
What are flagella?
Longer structures that exist by themselves or in pairs
Function like a propeller
What’s an example of a flagella?
Sperm cells
What is the break down of a 1% NaCl solution? (What is its concentration?)
1 molecule of NaCl for every 99 water molecules
When there’s a concentration gradient…
There’s a different concentration of molecules on one side of a membrane
Define: Hypertonic, Isotonic, Hypotonic
Hypertonic: a solution with higher solute concentration
Isotonic: a solution with equal solute concentration
Hypotonic: a solution with less solute concentration
When do molecules NOT move from an area of high concentration to low concentration?
If a barrier is present restricting movement
Diffusion is…
Molecules moving down a gradient from high concentration to low concentration
More molecules will get bumped out than those that get bumped in
Solution A is 30% sugar- is the solution hypothonic/hyper/iso/none?
None! We have to compare it to another solution
Solution A is 30% sugar, solution B is 10% sugar…
Solution A is hypertonic to solution B
Inside the cell is 98% water, outside the cell is 70% water
The cell is hypertonic to surroundings