Mod 3: Cells Flashcards
What is selective permeability in relation to the plasma membrane?
Some substances, such as lipid-soluble molecules, pass through easily, while others do not
What is diffusion?
Involves the movement of particles from an area of higher concentration to an area of lower concentration
(dye tablet in water)
What is osmosis?
Involves the diffusion of water down the concentration gradient through a selectively permeable membrane
A difference in concentration of a substance from one point to another is called
Concentration gradient
A solution with the SAME concentration of solutes as that inside the cell
Isotonic
A solution with a HIGHER concentration of solutes as that inside the cell
Hypertonic
A solution with a LOWER concentration of solutes as that inside the cell
Hypotonic
What would happen to a red blood cell in an isotonic solution?
Cells remain normal in size and water content
Water moves in and out of the cell at an equal rate
What would happen to a red blood cell in a hypertonic solution?
Water will diffuse out of the cell, causing it to shrivel and perhaps die
What would happen to a red blood cell in a hypotonic solution?
Water will move by osmosis into the cell. This influx of water will cause the cell to swell and eventually burst (called lysis)
What is the role of the sodium – potassium pump?
- Regulates the volume of fluid within cells
- provide electrical potential necessary for nervous system activity
- helps in heat protection
What happens in the sodium-potassium pump?
- Three sodium ions inside the cell funnel into receptor sites on a channel protein, fueled by ATP, the channel protein releases them into extracellular fluid.
- meanwhile, two potassium ions from outside the cell enter the same channel, the potassium ions are then release inside the cell.
- this keeps the concentration of potassium higher, and the concentration of sodium lower within the cell
What is another name for white blood cells? And what is their primary role?
Leukocytes - cells of the immune system that protects the body from infections and foreign invaders
What is active transport?
A movement of solutes up the concentration gradient from areas of lesser to greater concentration. (Like swimming upstream, requires energy)
What happens in filtration?
Water and dissolved particles are forced across the membrane from an area of higher to lower hydrostatic pressure
What is facilitated diffusion?
Helps other molecules move across the membrane
What is endocytosis?
The form of vesicular transport that brings substances into the cell
Endo = take in
What is phagocytosis?
Occurs when the cell engulfs a solid particle and brings it into the cell
“Cell eating”
What is pinocytosis?
Occurs when tiny vacuoles bring droplets of extracellular fluid containing dissolved substances into the cell. The cell then uses the engulfed fluid and nutrients.
“Cell drinking”
What is exocytosis?
Uses vesicles to release substances outside of the cell.
Glands often use this method to release hormones
What are the building blocks of DNA?
million pairs of nucleotides, each consists of one sugar, one phosphate group, and one of four possible types of nitrogenous bases. 4 bases are adenine, thymine, guanine, cytosine.
Why does DNA need help from RNA?
Do you need is too large to leave the nucleus, and protein synthesis takes place in the cytoplasm.
What are the 3 forms of RNA that are crucial for protein synthesis?
Messenger RNA, transfer RNA, ribosomal RNA
What is transcription?
1st step of gene expression - it involves copying a genes DNA sequence to make an RNA molecule.
What is translation?
Once in cytoplasm, mRNA attaches to a ribosome, which consists of rRNA and enzymes. There begins process of being “translated” into a protein. The ribosome moves along the strand of mRNA reading the codons
What happens in the first sequence of the cell cycle - first gap phase - G1?
It accumulates the materials it will need to replicate its DNA
What happens in the second sequence of the cell cycle (synthesis phase) ?
DNA replication - Cell makes an extra set of DNA
What happens in the 3rd sequence of the cell cycle - second gap phase - G2?
Preparation for mitosis. The cell makes final preparations for cell division, including synthesizing necessary enzymes.
What happens in the 4th sequence of the cell cycle - mitotic phase?
Cell division occurs
What happens in the prophase of mitosis?
Chromosomes appear
What happens in metaphase?
Chromosomes line up along the centre of the cell
What happens in anaphase?
Chromosomes are pulled to opposite poles by spindle fibres
What happens in telophase?
Two new cells are formed
