Human Bio Flashcards
Cell Membrane:
The outer boundary of the cell that separates it from neighboring cells and from the external environment. Determines which substance gets in and out.
Golgi Body:
Flattened membranous bags stacked on top of each other. They modify proteins and package them in vesicles for secretion from the cell.
Vesicle:
A membrane bound sac that transports materials into, out or within the cell.
Mitochondria:
Spherical and elongated structure spread through the cytoplasm. Mitochondria release energy for the cell through the process of respiration.
Nucleus:
Usually ovoid or spherical. Contains the genetic material, mostly DNA, separated from the cytoplasm by a nuclear membrane. It has nuclear pores where large molecules can pass through.
Nucleolus:
Is composed mainly of RNA. The DNA and nucleolus are suspended in a jelly-like nucleoplasm.
Cytoplasm:
Thick fluid within the cell membrane and all the structure suspended in it. Cytosol is the liquid part of the cytoplasm. 75-90% water.
Centrioles:
A pair of cylindrical structures usually located near the nucleus, involved in the reproduction of the cell.
Endoplasmic Reticulum:
Pairs of parallel membranes extending through the cytoplasm and connecting the cell membrane with the nuclear membrane. Provides a surface on which chemical reactions can occur. The channels between the paired membranes are used for storage or to transport material. Most ER have ribosomes attached while some don’t.
Ribosomes:
Very small and spherical. Amino acids are joined together at the ribosomes to make proteins.
Cytoskeleton:
Consist of microfilaments and microtubules that give the cell its shape and assist the movement of the materials.
Lysosomes:
Small spherical that contain enzymes able to break down proteins, lipids, nucleic acids and some carbohydrates. Lysosomes break down materials that are taken into the cell or break down worn out organelles.
Inclusion:
Substances that are not part of the cell structure but are found in the cytoplasm.
Types of Transport through the cell membrane:
1.Simple diffusion
2.Faciliated transport
3.Vesicular Transport
What is passive transport?
Passive transport does not require any energy and the substances move with the concentration gradient.
What is active transport?
Active transport does require energy and substances move against the concentration gradient.
Passive Transport simple diffusion:
The spreading out of particles is brought out due to more collisions happening with the particles at high concentrations.
This forces them to move away from each other into areas with low concentration where they experience less collisions.
Diffusion
The spreading out of particles from areas of high concentration to areas of low concentration resulting in even distribution.
Simple Diffusion: Concertation Gradient
The difference in concentration that brings about diffusion is known as concentration gradient. The greater the difference between the two concentrations faster the rate of diffusion.
Passive Transport Facilitated Diffusion:
Definition of Diffusion but occurs through a channel protein. Generally used for water molecules and ions as they are polar molecules. Polar molecules cannot pass through the phospholipid bilayer.
Passive Transport Osmosis
Osmosis: The diffusion of a solvent(water) through a differentially (semi) permeable membrane.
The solvent is able to move through the membrane but the solute is not able to fit through.
The only way to reach equilibrium is for the solvent to move.
Passive Transport Osmosis and Tonicity.
Tonicity is the concentration of a solution as compared to another solution.
Isotonic: Extracellular and intracellular ionic concentration equal.
Hypotonic: Extracellular ionic concentration is less than intracellular
Hypertonic: Extracellular ionic concentration is more than intracellular.
Active Transport
Definition of Diffusion + Occurs predominantly through carrier proteins and requires energy. Useful when substances need to move against the concentration gradient such as sodium to maintain the osmotic pressure.
Vesicular Endocytosis
The taking in of solids or liquids through vesicles.
Cell membrane folds around the substance until it is completely enclosed.
Vesicle then pinches off within the cytoplasm.
Pinocytosis - taking in liquids(cell drinking)
Phagocytosis - taking in solid particles.