BIOL 1306 Test 3 Study Guide

free energy

• represents the energy available to do work in a system at constant temperature and pressure

• determines the spontaneity and direction of reactions

• drives an endergonic reaction when released from an exergonic reaction

exergonic

• have a negative charge

• energy of products is LOWER than energy of reactants

• spontaneous but may still require an initial input of energy to overcome the activation energy barrier

endergonic

• have a positive charge

• energy of products is GREATER than energy of reactants

• not spontaneous & needs energy to start the reaction

catabolism

• reactions that break down molecules and release energy

• occurs in digestion, glycolysis, the citric acid cycle, oxidative phosphorylation, etc.

• eg. hydrolysis reactions

anabolism

• synthesizing complex molecules and polymer by forming covalent bonds

• requires energy input (often times from catabolism)

• eg. dehydration reactions

activation energy

• the minimum energy required to initiate a chem. reaction

• energy required to change reactants from a stable to unstable state where electrons can be arranged

active site

• the region of the enzyme that interacts with the substrate

• has a unique structure and chemical properties with high selectivity that will bind to specific substrates

• can be reused

substrate

• reactant specific for a particular enzyme

• can be simple molecules, complex molecules, and nucleic acids

catalyst

• accelerates a chemical ration by decreasing activation energy

• is not consumed during the reaction

enzyme activity

• the rate at which the enzyme converts substrates to product(s)

• depends on temp and pH

  • 3D shape of protein can change, which alters its function

competitive inhibtor

• attaches to the active site and blocks substrates from entering

• reduces the activity of an enzyme

allosteric inhibitor

• attaches to another region or enzyme

• changes enzyme’s shape so the active site no longer grabs the substrate and altering the enzyme’s function

Interphase

• where the cell spends most of its life

• between one M phase and the next

• includes G1, S phase, and G2

S phase

• stands for synthesis of DNA

• where chromosomes are copied to prepare for cell division

• 2nd phase in interphase

G1

• where the cell grows, goes through cellular respiration, protein synthesis, and membrane transport

• 1st phase in interphase

In where does G1 causes cells to divide frequently?

epithelial cells and blood stem cells

In where does G1 may last for years and division can occur to repair injury?

liver cells

In where do certain cells remain in G0 after puberty and do not divide?

muscle cells and some nerve cells

G2

• where the cell prepares for mitosis and ensures all DNA is replicated and any damage is repaired

• final phase of interphase

mitosis

• the process of cell division that results in two identical daughter cells, which have chromosomes and genes identical to the parent

• involves prophase, metaphase, anaphase, and telophase.

Mitotic normal function

• Reproduction of single-celled organisms (eg. amoeba)

• Development from zygote to embryo and growth to adult

• Renewal of tissues, especially epithelium

• Centrosome: point of origin for microtubules

cytokinesis

• division of the cytoplasm to form two daughter cells, each with its own nucleus

• occurs immediately after cell division by mitosis/meiosis

• facilitated by the formation of a cleavage furrow

centrosome

• point of origin for microtubules

• crucial to organizing microtubules during cell division and maintaining the overall structure of the cell

• help form the spindle fibers that separate chromosomes

• duplicated during the cell cycle

centromere

• the point on a chromosome at which sister chromatids are closely attached

• contains DNA sequences

• where the spindle fibers attach to the chromosome to ensure proper segregation

• where the kinetochore forms

chromosome

• one double-stranded molecule of DNA wound around histone proteins

• 2 sets of 23 (one from mother, one from father)

chromatid

• one of the two identical double-stranded DNAs that are connected at the centromere and compose a replicated chromosome (sister)

• each has a kinetochore associated with its centromere

prophase

• chromosomes condense

• spindle apparatus forms

• 2nd centrosome forms

• nuclear envelope begins to breakdown

• nucleolus disappears

• cytoskeleton of interphase is dismantled

1st phase of mitosis

prophase

spindle apparatus

array of microtubules responsible for organizing and moving chromosomes during cell division

centriole

• one of two small cylindrical structures contained within the centrosome near the nucleus of a eukaryotic cell

• plays a role in the organization of the mitotic spindle

prometaphase

• nuclear envelope breaks down and disappears

• centrosomes are at opposite poles

• spindle fibers attach to kinetochores or interact with microtubules from opposite pole

2nd phase of mitosis

prometaphase

kinetochore

• protein structure that links the centromere to the spindle fiber

• facilitates the attachment of chromosomes to the mitotic spindle

• involved in chromosome segregation during cell division

metaphase

• chromosomes are in the middle of the spindle

• kinetochore of each chromatid is attached to the microtubule from the opposite pole

• centrosomes at opposite poles

3rd phase of mitosis

metaphase

anaphase

• sister chromatids separate

• kinetochore microtubules shorten

• chromosomes move to opposite poles of the spindle apparatus

4th phase of mitosis

anaphase

telophase

• chromosomes de-condense back into chromatin

• nuclear envelope re-forms, making 2 nuclei

• spindle microtubules break down/depolymerize

• nucleoli re-appear, making ribosomes

• rebuilding of interphase cytoskeleton

5th & final phase of mitosis

telophase

cleavage furrow

• an indentation in the cell surface that occurs as the plasma membrane is pulled inward during cytokinesis

• deepens until the membrane fuses, dividing the cytoplasm into two daughter cells

adaptation

• heritable characteristics that enhances survival and reproduction

• good enough but not perfect

• frequency can change between generations

acclimatization

short-term change in an individual’s physiology in response to a change in the environment

conformer

• an organism that adjusts to its environment, allowing its internal conditions to change with external factors

• ectotherms, such as fish, amphibians, and reptiles

• limited range of environments to survive in

regulator

• an organism that maintains homeostasis and regulate internal conditions despite changes in the external environment

• uses energy to counteract environmental changes

• endotherms, such as birds and mammals

homeostasis

maintaining a predictable and stable internal environment

insulin

• peptide hormone

• secreted by the pancreas in response to high levels of glucose in the blood

• enables cells to absorb glucose

glucagon

• peptide hormone

• secreted by the pancreas in response to low blood glucose levels

ectotherm

• cold-blooded

• source of heat from the external environment

• eg. fish, amphibians, and reptiles

endotherm

• warm-blooded

• source of heat from the internal metabolism

• eg. birds and mammals

convection

heat transfer by a moving fluid

conduction

heat transfer between objects in direct contact

radiation

• electromagnetic radiation

• any object warmer than 0 K radiates infrared

evaporation

• liquid molecules with the highest kinetic energy escape into the gas phase

• removes heat from the animal

osmolarity

• The concentration of dissolved solutes in a solution, measured in osmoles per liter

• moles solute particles/L

• units: mosm/L

• (# of ions)(concentration)

  • eg. 50 mM NaCl sol’n - ionic, dissociates into (2) ions -> (Na+ and Cl-)

    • 2 x 50 mM = 100 mOsm

  • eg. 50 mM glucose sol’n - covalently bonded, doesn't dissociate

    • 1 x 50 mM = 50 mOsm

hyposmotic

• a solution that has a LOWER solute concentration & HIGHER water concentration than another solution

• swelling and cell lysis

hyperosmotic

• a solution that has a HIGHER solute concentration & LOWER water concentration than another solution

• dehydration

• cell shrinkage

ammonia

• NH3

• is the byproduct of the breakdown of proteins and nucleic acids in cells

• is a metabolic waste that is excreted

• toxic to cells

• major nitrogenous waste of bony fishes and aquatic invertebrates

urea

• synthesized from NH3 by vertebrate liver

• less toxic than NH3

• requires less H2O to excrete than NH3

• require energy to synthesize

• is a metabolic waste excreted by mammals, adult amphibians, sharks, and some marine fish

uric acid

• low toxicity

• generates H2O

• requires energy to synthesize from NH3

• is a metabolic waste excreted as a paste by birds, reptiles, insects, and snails

hemolymph

the circulatory fluid of animals with open circulatory systems (eg. insects), in which the fluid is not confined to blood vessels

interstitial fluid

fluid in extracellular space surrounding body cells

interphase

prophase

prometaphase

metaphase

anaphase

telophase

What is the ploidy level at the beginning of cell division?

diploid (2n); 46 chromosomes

What is the ploidy level at the end of cell division?

diploid in each identical daughter cell (2n); 46 chromosomes

Daughter cells are genetically

identical to the parent cell

counter-current exchange of heat between blood vessels entering and exiting an appendage

• a physiological mechanism that helps conserve body heat in animals, especially in cold environments

• occurs when two blood vessels—one carrying warm blood from the core of the body and the other carrying cooler blood from the appendage—pass in close proximity to each other and exchange heat in opposite directions

artery

carries warm blood from the body’s core toward the appendage

vein

returns cooler blood from the appendages back to the core of the body

Cholecystokinin (CCK)

• a hormone that helps regulate ingestion, digestion, and absorption of nutrients

• secreted by the small intestine

Gastrin

• a hormone produced from the stomach lining in response to the arrival of food or to a neural signal from the brain

• stimulates other stomach cells to release HCl

Secretin

• peptide hormone secreted by cells in the small intestine in response to the arrival of food from the stomach

• stimulates secretion of bicarbonate ions by the pancreas

Challenges to freshwater fish

• water gain

• salt loss

Solutions to challenges to freshwater fish

• Import NA+ and Cl- by active transport

• Excrete dilute urine

• Net result: solute conservation

Challenges to marine animals

• water loss

• salt gain

Solutions to challenges to marine animals

• Drink salt water

• Excrete Na+ & Cl- by active transport

• Net result: water conservation

Challenges to terrestrial animals

• dehydration

Solutions to challenges to terrestrial animals

• Nocturnal activity

• Waxy coating on the exoskeleton

• Keratinized skin

ammonia advantages

• low energy cost

• simple excretion

• small molecular size

ammonia disadvantages

• high toxicity

• requires a large amount of water

• limited to aquatic environments

urea advantages

• lower toxicity

• moderate water requirement

• more adaptable

urea disadvantages

• energy cost

• requires some water

uric acid advantages

• low toxicity

• minimal water loss

• ideal for water-conserving environments

uric acid disadvantages

• high energy cost

• waste accumulation

• potential for solid waste

Why does excreting urea or uric acid requires energy?

both processes involve detoxifying ammonia (a byproduct of protein and nucleic acid breakdown) and converting it into less toxic forms, which requires energy

solute movement across transport epithelia in marine vertebrates

focus heavily on salt excretion and water conservation to maintain osmotic balance in a hyperosmotic environment (salt water), with specialized gill cells and salt glands

solute movement across transport epithelia in mammalian kidney

adapted for a broader set of functions, including waste excretion, regulation of electrolyte balance, and water conservation in a hypoosmotic environment (terrestrial life)

step 1 of reabsorbing water across the kidney epithelium

Na⁺-K⁺-ATPase in basolateral membrane creates a Na+ gradient

step 2 of reabsorbing water across the kidney epithelium

Na+ gradient drives the co-transport of glucose, Cl- & vitamins into cells through co-transporters in the apical membrane

step 3 of reabsorbing water across the kidney epithelium

high solute concentration makes epithelial cell hyperosmotic to blood

step 4 of reabsorbing water across the kidney epithelium

each solute diffuses across the basolateral membrane and reenters blood

step 5 of reabsorbing water across the kidney epithelium

H2O diffuses through aquaporins in apical membrane and in basolateral membrane

step 6 of reabsorbing water across the kidney epithelium

H2O reenters blood

Describe solute movement across transport epithelia in fish gills

there is a countercurrent exchange of O2 between blood and water (where water flows over the gill filament in the opposite direction from the blood flowing inside the gill filament), which maximizes O2 diffusion into the blood and prevents equilibrium PO2 from developing between water and blood

What would happen to the blood osmolarity if Na⁺-K⁺-ATPase is inhibited in the nephron epithelial cells of a terrestrial vertebrate?

• disruption of sodium and water reabsorption in the kidneys

• reduced generation of the osmotic gradient necessary for eater reabsorption

• increased urine volume with more dilute urine

• increased blood osmolarity

• potential dehydration and electrolyte imbalances

What would happen to the blood osmolarity if the number of aquaporins increases in a terrestrial vertebrate's epithelial cell membrane?

• more water reabsorbed from the filtrate into the blood

• less urine produced, and urine is more concentrated

• blood osmolarity decreases (more water in the blood)