A&P quiz 2 review

structure of the cell membrane

structure of the cell membrane

separates the cells internal environment from the external environment

regulates the movement of materials into and out of the cell

composed of phospholipids, cholesterol, carbohydrates and proteins

flexible, dynamic structures

phospholipids

major structural component of the cell membrane

Amphipathic molecule (hydrophilic head (contains phosphate group) hydrophobic tails (non polar)

organized into bilayers to form biological membranes nd h

Cell membrane structure

selectively permeable

composed mostly of phospholipid bilayers

intracellular fluid (ICF) inside of cell (Cytosol)

extracellular fluid (ECF)

proteins also associated with the cell membrane

membrane proteins

add functionality (serve as channel proteins, receptors, enzymes, and in cell-cell recognition

transmembrane (integral) proteins

span the entire width of the cell membrane

peripheral proteins

do not span membrane

attached to the interior of exterior of the membrane

glycoproteins

proteins that have carbohydrate molecules attached

add in cell recognition

glycocalyx

formed by numerous glycoproteins

only in some cells

can serve as receptors for hormones and a means to bind to othe cells

helps break down nutrients

selectively permeable

allows only small, non polar molecules to pass freely

flow

gradient/resistance

occurs from high to low concentration unless prevented by resistance

molecules able to pass with flow across the membrane if there is a gradient

passive transport

movement does not require energy

requires concentration gradient

2 types:

1. simple diffusion

2. facilitated diffusion

simple diffusion

molecules move from higher to lower concentration without the use of membrane proteins

facilitated diffusion

molecules move from higher to lower concentration through membrane proteins

simple diffusion across a cell membrane

small, non polar molecules can pass through the cell membrane

diffusion continues until a net equilibrium is reached

diffusion occurs faster at higher temp

facilitated diffusion across a cell membrane

requires assistance of transmembrane proteins

molecules still move down concentration gradient

used for molecules that cannot diffuse through the cell membrane (polar or ionic molecules)

osmosis

the movement of water across the cell membrane

from high solute to higher solute concentration

hypotonic solution

less solute outside of cell

water enters cells when they are in hypotonic solutions

hypertonic solution

more solute outside of cell

water will leave cells in hypertonic solutions

isosmotic solutions

have equal concentrations of solute

hyperosmotic solutions

solution contains more solute by comparison

hypoosmotic

contains less solute by comparison

tonicity

describes the osmolarity of the ECF compared to the cytosol of the cell

isotonic in cells

equal concentration across cell membrane

cell functions normally

hypertonic solutions in cells

more solutes in the environment

cell shrinks

hypotonic solution in cells

fewer flutes in the environment

cell swells and may burst

active transport

requires energy to move molecules against their concentration gradient

from low areas of [ ] to areas of higher [ ]

primary active transport

uses ATP as energy source

secondary active transport

uses electrochemical gradient as energy source

• symporters move two molecules in the same direction

• antiporters mover two molecules in opposite directions

sodium potassium pump

primary active transport

uses ATP to move 3 sodium ions of the cell and 2 potassium ions into the cell, against the [ ] gradients

endocytosis

a form of active transport

uses cell membrane to engulf materials

cell membrane pinches off to form a vesicle and materials enter the cell.

three forms:

1. phagocytosis

2. pinocytosis

   1. receptor-mediated endocytosis

phagocytosis

extends the cell membrane to bring in large molecules

pinocytosis

membrane invagination brings in small amounts of fluid containing dissolved substances

receptor mediated endocytosis

ligand binds to membrane receptor for cellular entry

more selective

exocytosis

cell exporting materials or cell secretion

vesicle fuses with cell membrane

contents are released from cell

hormones and digestive enzymes secreted this way

cytoplasm

the fluid like interior if cells including its compartments and organelles

organelles

membrane bound structures that perform specific functions

cytosol

gel like substance within the cytoplasm

contains organelles and molecules needed by the cell

ER

series of channels continuous with the nuclear membrane; provides passages for synthesis, transportation and storage

rough ER

contains ribosomes

involved in protein synthesis

smooth ER

involved in lipid synthesis

Golgi apparatus

series of flattened sacs

sorts and modifies products from rough ER for transport

cis-face receives products for modification

trans-fase releases products after modification

lysosomes

membrane bound vesicles that contain digestive enzymes

used to break down wastes within cell

peroxisomes

contains enzymes used to produce hydrogen peroxide

used for detoxification and lipid metabolism

mitochondria

site of aerobic respiration

responsible for nutrient breakdown and ATP production

energy transformer of the cell

bilayer: outer membrane and inner membrane (folded into cristae)

more numerous in muscle and nerves

cytoskeleton

helps maintain the structure of the cell

organizes cytoplasm

aids in separation during cellular division

composed of protein filaments that provide support

1. microtubules - made of tubules

2. intermediate filaments - made of keratin

3. microfilaments - made of actin

dynamic nature of cytoskeleton

not fixed

components form and can move depending on needs of the cell

helps move molecules and structures around interior of cell

microvilli

help increase surface area of the cell

cilia

aid in movement of the cell or movement across the surface of the cell

nucleus

houses DNA of the cell

most human cells have a single nucleus

nucleus is surrounded by a nuclear envelope

nucleus within nucleus

nucleic acids found in human cells

DNA, mRNA, tRNA, rRNA

mRNA

is used in translation of proteins

tRNA

moves amino acids during translation

rRNA

is structural components of ribosomes

4 nucleotide bases of DNA

1. Adenine (A)

2. thymine (T)

3. cytosine (C)

4. guanine (G)

adenine forms a double bond with thymine

cytosine forms a triple bond with guanine

organization of DNA

strands are wrapped around histone proteins for organization

chromatin is the loose form of DNA

chromatin is packaged to form chromosomes

protein synthesis within the cell

DNA contains the genetic code of the cell

genetic code provides the instructions to produce cellular proteins

protein production begins in the nucleus and ends in the cytoplasm

genes are transcribed into messenger RNA (mRNA)

mRNA is then translated into proteins

making protein from DNA

proteome is a cells full compliment of proteins

genes contain information necessary to make proteins

DNA is transcribed to mRNA

mRNA is then translated to proteins

transcription

process of creating a strand of messenger RNA (mRNA) from a DNA template

occurs within the nucleus of the cell

complementary mRNA is made from a gene of one strand of DNA

mRNA will leave the nucleus for translation

three stages of transcription

1. initiation- DNA strands are separated and RNA polymerase begins to synthesize complementary RNA molecule

2. elongation - RNA polymerase continues to add nucleotides to growing strand

3. termination - RNA polymerase reaches end of gene and mRNA transcript is released

creating a mature mRNA transcript

before leaving nucleus, mRNA transcript is modified

DNA contains regions that do not code for amino acids (called introns)

regions tha code for amino acids are called exons

interns must be removed before mRNA leaves nucleus

translation

process of creating a protein from mRNA template

occurs in the cytoplasm of the cell

carried out by ribosomes (ribosomal RNA (rRNA)-components of ribosomes

each there nuclides sequence of mRNA is a codon

ribosomes read codons

transfer RNA (tRNA) brings amino acids to ribosomes

• tRNA contains anticodons that match specific mRNA codon

process of translation

initiation - ribosome subunit attach to start codon of mRNA transcript

elongation - tRNA molecules are attracted to the ribosome and deliver the corresponding amino acids to the growing polypeptide

termination - translation continues until ribosome reached a stop codon that ends the process

Cell cycle

1. interphase

2. mitosis

3. cytokinesis

cell spends most of its time in interphase

interphase is split into

G1 phase - cell grows, makes proteins, and carries out cellular functions

s phase - cell replicates its DNA

G2 - cell prepares for mitosis

mitosis

occurs in somatic cells

• daughter cells are identical to parent cell

• cells contain 46 chromosomes or diploid number

Meiosis

occurs for reproductive cells

resisting cells have half the amount of genetic material from one parent and half the other

cells contain 23 chromosomes of the haploid number

S phase

process of coming DNA occurs in this phase

3 phases

• initiation: the DNA strands are separated by helices

• elongation: the DNA polymerase synthesizes a new strand

  • termination: the DNA replication stops

chromatin

the linear form of DNA

DNA replication

condensed into chromosomes during replication

replicated copy is called a sister chromatid

sister chromatids are attache at a centromere

chromatids separate during mitosis

• makes sure each daughter cell has a complete copy of DNA

phases of Nucleic Acid Processes

transcription, translation, replication are each divided into 3 phases:

• initiation

• elongation

• termination

mitosis

4 major phases by cytokinesis:

1. prophase

2. metaphase

3. anaphase

4. telophase

5. cytokinesis

prophase

chromatin condenses into chromosomes and the centrioles migrate to opposite sides of the cell

metaphase

chromatids align in the middle of the cell

anaphase

chromatids seperate-and move toward the opposite sides of the cell

telophase

nucleoli and nuclear membranes start to form and chromosomes return to chromatin form

cytokinesis

cleavage furrow divided cell into two distinct cells

factors that regulate cell division

growth factor

contact inhibition

• if cell is surrounded, it won’t divide

increasing efficiency

• larger cells are less efficient

stem cells

can differentiate into specific cell types

specific genes are turned on during differentiation

• transcription factors turn on necessary genes

• turning specific genes on in them cells produced certain proteins needed for the differentiated cells function

organic biological macromolecules

1. carbohydrates

2. lipids

3. proteins

4. nucleic acids

the chemistry of Carbon

organic molecules contain C bonded to H atoms

they can form chains or ring structures

Functional groups

C can bond to functional groups

• a group of atoms linked by covalent bonds that function as a unit

hydroxyl: -O-H

Carboxyl: O-C-OH

Amino: -N-H2

Phosphate: -P-O4²-

Methyl: -CH3

monomers

individual units that make up organic molecules

polymers

monomers bond together to form polymers

monomers of major organic molecules

1. carbohydrates: monosaccharides

2. lipids: fatty acids and glycerol

3. proteins: amino acids

4. nucleic acids: nucleotides

Carbohydrates

made up of C,H,O2

ratio of H to O2 is 2:1 (usually)

main source of chemical energy in the human body

important monosaccharides

glucose

fructose

galactose

ribose

deoxyribose

important polysaccharides

few to thousands of monosaccharides

starches- glucose storage in plants

glycogen- glucose storage in animals

cellulose- cell wall of plants

important disaccharides

common in human diet

sucrose-table sugar

lactose-milk sugar

maltose-malt sugar

function of carbohydrates

primary source of cellular energy

• used to produce ATP

help maintain cellular structure

• component of plant cell walls

can bond with lipids and proteins to form glycolipids or glycoproteins

• help form cell membrane and aid in cell signaling

lipids

made mostly of hydrocarbons

• non polar, hydrophobic molecules

triglyceride is the most common form in our diet

major energy source for cells

provides insulation

triglycerides

contains 3 - carbon glycerol molecule

3 fatty acids are attached to the glycerol

• each fatty acid is a long chain oh hydrocarbons

saturated fats

lipids tha have the maximal number of hydrogen atoms bound to carbon

• solid or semisolid at room temp

unsaturated fats

lipids that contain double bonds

• fatty acid tails zig zag as a result

• liquid at room temp

cholesterol

precursor used to make several hormones and provides stability to the cell membrane

prostaglandins

play a role in inflammation

proteins

composed of amino acids linked together by peptide bonds

function to provide cellular structure, transport substances, and catalyze reactions.

shape of proteins

1. primary

2. secondary

3. tertiary

4. quaternary

structure of amino acids

amino acids are the monomers of proteins

20 amino acids in total

each consists of an amino group, carboxyl group, and an R group

linked by peptide bonds to form proteins

peptide bonds

peptide bonds link amino acids

formed through dehydration synthesis

• carboxyl and amine groups of neighboring amino acids react.

amino acid interactions determine protein shape

amino acids may form hydrogen bonds

hydrophobic amino acids may huddle while hydrophilic amino acids surround them