Anatomy and Physiology unit exam 2

Chapters 3 and 25 on cells and metabolism. I hate cells and metabolism

Cell theory

smallest units of life

building blocks of all organisms

maintains homeostasis

Genetic code of proteins

three nitrogenous bases; it is a triplet code

genes

genes are a functional unit of heredity

they are DNA that code for particular proteins

gene activation

can turn off cells

allows for a gene to be transcribed; region of DNA must be uncoiled

genes have promoter region at the beginning and stop signal at end

coding strands

contain triplets that specify amino acids

Template strands

contain complementary triplets to make mRNA

Steps of transcription

1.DNA helix is separated, RNA polymerase is positioned at promoter

2.RNA polymerase moves along template strand and matches complimentary DNA

3.RNA polymerase detaches at stop signal and mRNA is released

RNA processing

occurs before mRNA leaves nucleus

Introns and exons

Introns are noncoding regions that are not needed to make protein. These are snipped

exons are coding regions that are required to make protein. These are spliced

Translation

occurs at the ribosome

an amino acid chain is formed using information in mRNA

anticodon

in translation and has a three base sequence complementary to mRNA codons

Steps of translation

1.Initiation - small ribosomal subunit binds to mRNA and tRNA carrying methionine binds to mRNA start codon

2.Initiation - large ribosomal subunit joins complex

3.Elongation - second tRNA arrives, carrying an amino acid

4.Elongation - process repeats with tRNA bringing amino acids to the ribosome. amino acids link together

5.Termination - ribosome reaches stop codon

Ribosomes

are made of proteins and ribosomal RNA. It has two subunits

Proteins

after proteins are made, they are modified and sent to golgi apparatus for packaging DNA

DNA has direct control synthesis of structural proteins and has indirect control over cellular metabolism through synthesis of enzymes

mutations

permanent changes

caused by errors in DNA replication or environmental factors

changes the function in protein

Cell life cycle

G0 - performing normal functions

G1 - Normal functions and cell growth

S - DNA replication and synthesis of histones

G2 - last minute protein synthesis

DNA replication

DNA molecule is double stranded, winds around proteins called histones

chromatin

easy access to make protein

chromosomes

tightly coiled in DNA

Histones

complex called nucleosomes

Steps of DNA replication

1.Double helix is unzipped

2.Enzymes make new strands

3.DNA replication is semiconservative and two identical DNA molecules are formed

Mitosis

PMAT

stem cells divide rapidly, muscle cells do not

Steps of mitosis

1.Early prophase - chromatin condenses into chromosomes

2.late prophase - nuclear envelope disappears

3.Metaphase - chromosomes align down the middle of the cell on metaphase plate

4.Anaphase - Connection between sister chromatids are broken; daughter chromosomes are pulled to opposite sides of the cell

5.Telophase - Nuclear envelopes reform around each set of chromosomes and they uncoil into chromatin

Cytokinesis

division of the cytoplasm

begins during anaphase and finishes during telophase

Plasma membrane functions

isolates cell

can detect changes

regulates waht can enter cell

stabilized position of cell

phospholipid bilayer

has hydrophilic heads at surface and hydrophobic tails in the middle

cholesterol

steroid that helps stiffen the membrane

Types of membrane proteins

channel proteins - allow water and small solutes to pass through

carrier proteins - transport solutes across membrane by changing shape

receptor proteins - bind to extracellular molecules, which can trigger changes into the cell

anchoring proteins - stabilize position

glycocalyx

membrane carbohydrate that makes up about 3% of plasma membrane

its functions are lubrication, protection, and anchoring cell

selective permeability

some things can come through and some things cannot

Active vs passive transport

active transport requires ATP and passive does not

Diffusion

net movement of substances from one area of high concentration to low

diffusion is determined by

concentration gradient (steeper = faster), distance (shorter = faster), size of ion/molecule (smaller = faster), and temperature (higher = faster)

Types of diffusion

channel mediated diffusion: leak channels are always open, gated channels open and close in response to specific stimuli THIS IS FOR SMALL SUBSTANCES

Simple diffusion: substances are able to move directly through the phospholipid bilayer THIS IS LIPID SOLUBLE

Facilitated diffusion: substances too large to fit through channels must be moved by a carrier protein THIS IS FOR LARGE MOLECULES

osmosis

diffusion of water across a membrane

osmolarity

is the total solute concentration

tonicity

how a solution affects a cell

isotonic vs hypotonic vs hypertonic

isotonic - solution that does not cause a net osmotic flow of water into or out of the cell

hypotonic - solution causes cell to gain water. Hemolysis is the bursting of cells

hypertonic - solution causes cell to lose water. Crenation is shriveling of cells

Active transport

carrier proteins using ATP to move solute across the membrane

The sodium potassium pump

resting conditions in cells (HOMEOSTASIS)

Na+ is high in ECF and low in ICF

K+ is low in ECF and high in ICF

the pump ejects 3 Na+ and reclaims 2K+ for every ATP used

Endocytosis

formation of endosomes (vesicles) at plasma membrane to bring large amounts of substance into the cell

Exocytosis

vesicle fuses with plasma membrane and releases contents outside of cell

phagocytosis

solid objects

Metabolism

all chemical reactions in the body

catabolism vs anabolism

catabolism - decomposition reactions breaking larger molecules into smaller ones. Involves the production of ATP

anabolism - synthesis reactions: using smaller molecules to make larger ones. Repairs, growth, production of secretions, storing nutrient reserves. Typically requires ATP

Oxidation

loss of electrons, decrease in potential energy

reduction

gain of electrons, increase in potential energy

most energy changes and transfers in cells involve redox reactions

OIL RIG

Oxidation Is Lost, Reduction Is Gained

Coenzymes

help transfer electrons from one molecule to another

NAD and FAD remove hydrogen atoms from organic molecules

Mitochondria have

protein complexes called electron transport chains

the energy released in the redox reactions is used to generate ATP

Where do we get glucose

food

glycogenolysis - breakdown of glycogen stores in liver, skeletal muscle (mostly happens in liver)

gluconeogenesis - synthesis of glucose from non-carbohydrate precursors

What are the uses of glucose

glucose catabolism - broken down for ATP production

glycogenesis - formation of glycogen

can also be used to synthesize triglycerides, some amino acids

glucose catabolism

generates approximately 30-32 ATP

Occurs in a series of small, enzymatically-regulated steps

Types are glycolysis, citric acid cycle, electron transport chain

Glycolysis

occurs in the cytosol

anaerobic, does not require oxygen

The first step is phosphorylating glucose

Hydrogens are removed and transferred to NAD, producing 2 NADH

4 ATP are produced, and two 3-carbon molecules of pyruvate are produced from one 6-carbon glucose

KNOW HOW TO DRAW IT OUT

What happens to pyruvate

pyruvate still contains a lot of potential energy in its chemical bonds

if oxygen levels are low, it is converted into lactate

if oxygen is available, it moves into the mitochondria for the citric acid cycle

The citric acid cycle

occurs in the mitochondrial matrix

aerobic, requires oxygen

The preliminary step converts 3-carbon pyruvate to 2-carbon acetyl group

acetyl CoA combines with a four carbon molecule, forms a six carbon, two carbons and hydrogens removed, regenerating four carbon molecule

Products from the citric acid cycle preliminary step

3 CO2

4 NADH

1 FADH2

1 ATP

Products for the citric acid cycle

2 Co2, 1 ATP, 3 NADH, 1 FADH2

Electron transport chain

A series of proteins and electron carriers in the inner mitochondrial membrane

NADH and FADH2 drop off their electrons here, and at the end of the chain the electrons are transferred to oxygen

oxidative phosphorylation

the energy released in the ETC is used to generate 90% of our ATP

The three simultaneous processes in ETC

1.NADH and FADH2 deliver hydrogen atoms to the ETV

-Hydrogen ions are released into matrix and electrons are passed down the chain

-redox reactions

2.The energy released in the redox reactions is used to pump H+ into the intermembrane space

-This creates a gradient for H+

3.A protein complex in the inner membrane called ATP synthase contains an ion channel for H+

-The kinetic energy of the H+ ions moving through the channel is used by ATP synthase to make ATP

Oxygen in ETC

Oxygen is the final electron acceptor in the ETC

Without oxygen, we would not be able to make enough ATP to survive

Summary of products for glycolysis

2 NADH - move to the ETC

2 ATP - used by the cell

2 Pyruvate

Lipid catabolism

called lypolysis

triglycerides are broken down into glycerol and fatty acids

glycerol is converted to pyruvate

fatty acids are broken down into 2-carbon acetyl groups in a process called beta oxidation

Lipid anabolism

called lipogenesis

synthesis of most lipids begins with acetyl-CoA

Acetyl CoA can be made using carbohydrates, lipids, amino acids

Protein metabolism

amino acid catabolism: amino acids can be converted into substances that can enter the citric acid cycle

Deamination

removal of an amino group

from protein metabolism

produces an ammonium ion

urea

excreted from urine

Carbohydrates

primary source of energy for most cells

glucose is small and solluble

a small amount of ATP can be produces without oxygen

Lipids

secondary source of energy

catabolism results in more ATP produced than the equivalent amount of glucose

LIPIDS ARE INSOLUBLE AND STORED IN COMPACT DROPLETS

ATP production from lipids requires oxygen

Proteins

last resort

proteins have complex structures and are difficult to break down

amino acid catabolism produces ammonium - TOXIC

catabolism of proteins would disrupt homeostasis

Absorptive state of metabolism

occurs after a meal

cells absorb nutrients for growth, maintenance, and energy reserves

Postabsorptive state of metabolism

Body relies on internal energy reserves

need to maintain blood glucose levels

molecules used as energy reserves (glocogen, triglycerides, proteins) can be broken down