WEEK 2: Cells Flashcards
What is the body’s hierarchy of complexity?
- Chemical Level
- Cellular Level
- Tissue Level
- Organ Level
- System-Level
- Organismal Level
What are the main different sections of the cell?
- Plasma Membrane = flexible, selectively permeable membrane that allows for cellular conditions to be maintained.
- Cytoplasm = made of cytosol which is the fluid portion inside of the cell. Also holds organelles.
- Nucleus =
Contains the cell’s genetic material and is separated via a nuclear membrane.
Mitochondria: appearance and function
Appearance:
- double membrane bound organelle
Function:
- produces ATP
- mitochondrial crista (the folds in the inner membrane) create large surface area to generate space for frequent reactions to take place
- cells that are highly active have high quantities of mitochondria
Endoplasmic Reticulum: appearance and function
Appearance:
- series of tubules in the cytoplasm that is continuous with the nucleus
Function:
ROUGH = with ribosomes. Produce proteins for export.
SMOOTH = without ribosomes. It produces fatty acids and steriods.
Ribosomes: appearance and functions
Appearance:
- flattended and spherical in shape
- attached to RER
Function:
ON RER:
- produce proteins for export
FREE:
- produce proteins for domestic use (local cell use)
Golgi Apparatus: appearance and function
Appearance:
- a stack of flattened cisternae and associated vesicles.
- located near the ER
Function:
- works with the ER to transport, modify and package proteins into vesicles for delivery
- found in high levels in cells responsible for secretion (endocrine system - hormone production).
Lysosomes: appearance and function
Appearance:
- spherical bodies surrounded by a single membrane
Function:
- filled with digestive enzymes that digest excess or damaged parts of the cell
- do so via apoptosis (programmed cellular death)
- degrade material taken up from outside the cell and digest obsolete components of the cell itself.
Nucleus: appearance and function
Appearance:
- larger organelle
- large dot in centre is nucleolus
Function:
- largest organelle and the control centre
- contains hereditary units (genes) that are arranged into chromosones
What is the plasma membrane?
The external boundary of a cell, is made up of a phospholipid bilayer.
It regulates the passage of substances into and out of the cell.
What are the layers of the membrane?
The membrane is a phospholipid bilayer = made of a phosphate head and two fatty acid tails.
HYDROPHILIC HEAD = attracts water (sit on the outside)
HYDROPHOBIC TAIL = water fearing (sits on inside).
Hydrophobic molecules pass through the cell membrane, if they small enough, because they are water-hating like the interior of the membrane. Small lipids and steroids are hydrophobic and can readily cross the membrane.
Hydrophilic molecules cannot pass through the cell membrane—at least not without help—because they are water-loving like the exterior of the membrane, and are therefore excluded from the interior of the membrane.
Name the four functions of the membrane
- Barrier between the inside and outside of a cell.
- Allows cell to be selectively permeable (permits some and restricts other substances)
- Transport substances into and out of cell
- Cell-to-cell recognition
Forms of cellular transport
- simple diffusion
- protein channels (active or passive)
- vesicular transport (exoctosis or endocytosis)
What is simple diffusion?
- when fat or liquid soluble molecules move through the phospholipids easily
- move from an area of high to low concentration
- move down a concentration gradient
CONCENTRATION GRADIENT = a difference in the concentration of a substance from one place to another.
What is protein channel transport?
- integral proteins imbedded in the membrane open and close to transport ions
ACTIVE:
- when energy is required to transport
- occurs when transport goes against the concentration gradient i.e., the sodium-potassium pump
PASSIVE:
- move without concentration gradient
What is vesiculuar transport?
- transport proteins and other molecules
EXOCYTOSIS = releasing to outside the cell
ENDOCYTOSIS = bringing into the cell
VESICLE = a sac that contains components that need to be secreted. It fuses with the membrane to expel products. Or the opposite for endocytosis.
