Histology

exam #1 study guide

Simple Diffusion

**define**: mostly involves nonpolar solutes *(such as hydrocarbons and lipids, and gases such as O2 and CO2)* that pass straight through the phospholipid bilayer without assistance from a membrane protein

**material being moved:** nonpolar molecules, lipids, and CO2

**energy source:** no atp required

Facilitated Diffusion

**define:** involves charged or polar solutes *(such as ions and glucose)* that cross the phospholipid bilayer with the help of a membrane protein.

**material being moved:** polar and charged molecules (amino acids, carbohydrates, ions, nucleosides)

**energy source:** no atp required *(move from higher concentration to lower concentration gradient)*

Primary Active Transport

**define:** a pump binds a solute and transports it against its concentration gradient using the energy from the hydrolysis of ATP

**material being moved:** Na+ and K+

**energy source:** chemical energy (ATP)

Secondary Active Transport

**define:** uses ATP to create a concentration gradient by pumping one substance across the plasma membrane

**material being moved:**

**energy source:** ATP indirectly

Define Osmosis:

Water moves an area of lower solute concentration to one of higher solute concentration

How does osmosis differ from simple diffusion?

Simple diffusion is when a substance moves through a membrane or in a solution with no help from transport proteins and in osmosis the water moves from a lower solute concentration to a higher solute concentration.

Define tonicity:

compare the solute concentrations of two solutions

Define osmolarity:

a measure of solute concentration, number of particles per liter of solution

Define Genetic Code:

a list of the amino acids coded for by a specific DNA triplet or mRNA codon

Define Transcription:

the process by which a specific gene is copied onto a complementary strand of messenger RNA during protein synthesis

Define Translation:

the process by which a messenger RNA transcript is read by a ribosome and an amino acid string is synthesized

Process of RNA synthesis:

a part of transcription

RNA polymerase enzymes make an RNA copy of a DNA sequence.

role of tRNA:

serves as a link b/w the messenger RNA molecule and the growing chain of amino acids that make up a protein

role of mRNA:

carries genetic codes from the DNA in the nucleus to ribosomes

role of rRNA:

help hold ribosomal proteins in place and help locate the beginning and end of the mRNA message

Define Cellular Respiration:

series of chemical reactions that break down glucose to produce ATP

What happens during G phase 1?

normal cell functions occur as well as cell growth

What happens during G phase 2?

cell continues to prepare for mitosis and cell division

What happens during S phase?

dna replicates producing 2 copies of each chromosomes

What happens during cellular division?

mitosis; the process of making new body cells

Describe DNA replication:

the result of mitosis where a cell creates two identical copies of its chromosomes (aka sister chromatids)

Define chromatin:

one extremely long DNA strand and its associated proteins

Define chromosomes:

a structure found inside the nucleus of a cell

function: allow DNA to be accurately copied during these cell divisions

Define chromatids:

one of the two identical halves of a chromosome that has been replicated in preparation for cell division

What occurs during interphase?

the cell is engaged in growth and copies its DNA

What occurs during prophase?

the nucleus envelope disappears and the DNA condenses and splits into chromatids and sister chromatids

What occurs during metaphase?

the sister chromatids line up in the middle and the spindle fibers begin to attach

What occurs during anaphase?

the spindle fibers pull the chromatids a part

What occurs during telophase?

reforms the nucleus and cytokinesis into two new cells (daughters cells)

What occurs during cytokinesis?

divides cytosol and organelles equally into the two daughter cells

Function of Plasma/Cell membrane:

Provides structural support, communication with other cells, regulation of transport into and out of the cell, and cell identification.

Function of cytoplasm:

Fluid cytosol, organelles, and cytoskeleton.

Function of cytosol:

Fluid portion of cytoplasm. The functions are to cite many cellular processes like protein synthesis, enzyme-catalyzed reactions take place and storage. 

Function of Nucleus:

Surrounded by nuclear envelope. Contains DNA and it is the primary location for producing RNA. 

Function of Golgi Apparatus:

Sorts and modifies, and packages proteins and other products made by the ER. 

Function of Rough Endoplasmic Reticulum (Rough ER):

Modifies and folds proteins made by ribosomes. Manufactures and assembles most components of the plasma membrane

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\*RIBOSOMES ARE MADE IN THE ROUGH ER

Function of Smooth Endoplasmic Reticulum (Smooth ER):

Store calcium ions and synthesize lipids. Detoxifies certain substances. 

Function of Mitochondria:

Synthesizes the majority of the cell’s ATP

Function of Cytoskeleton:

Network of protein filaments which supports the cell, helps create and maintain its shape, and holds organelles in place. It allows organelles to be transported within the cell. Involved in cellular movement and cell division.

Function of Lysosome:

Digests damaged organelles and products brought into the cell by endocytosis. Recycles damaged organelles. 

Function of Channels:

membrane proteins act as channels through which substances pass to enter or exit the cell.

Function of Carriers:

membrane proteins bind and transport substances into or out of the cell

Function of Receptors:

membrane proteins act as receptors, binding to a ligand to trigger a change in the membrane protein or the cell

Function of Enzymes:

Membrane proteins act as enzymes, catalyzing, chemical reactions.

Function of Structural Support:

Membrane proteins bind other proteins in the ECF and/or cytosol, supporting the cell. 

Function of Linking adjacent cells:

Membrane proteins link adjacent cells in a tissue together