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GWU / Biology / BISC 1005 / what is origin of life?

what is origin of life?

what is origin of life?


School: George Washington University
Department: Biology
Course: The Biology of Nutrition and Health
Professor: T scully
Term: Fall 2015
Cost: 50
Name: BISC Midterm Study Guide
Description: Here is my study guide for Professor Scully's Midterm in BISC 1005. The clicker questions and answers are highlighted in yellow.
Uploaded: 10/10/2015
15 Pages 7 Views 14 Unlocks

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 An ecosystem consists of all the living and non-living factors in a  defined area

what is origin of life?

o Living: Biotic ingredients

 Organic molecules, proteins, nucleic acids, fats,  


o Non-living: Abiotic ingredients

 It took about 10 billion years for living things to come to  come into existence, so until that happened abiotic  

ingredients came about

 Atoms

 Hydrogen was the first stable atom that was formed  

as the universe aged

 More reactions occurred to make bigger atoms

 Origins of life

o Earth did not originally have oxygen If you want to learn more check out What is the most common form of spore dispersal?
If you want to learn more check out Which of the following is a reason why direct supervision is expensive?
We also discuss several other topics like Where does waste occur?
Don't forget about the age old question of Common for people who are self-actualized?
If you want to learn more check out What impact did the market revolution have American social, economic, political, and familial relations?

o Within waters, complex substances began to form that became  organic molecules

 Some of these contained at least one carbon and one  hydrogen atom hydrocarbons

o Biotic ingredients came together and compounds were formed  Created our common ancestors

 We came from a single common ancestor

 Components of this ancestor

what is symbiosis?

o Cell membrane

 Fatty inside, water-loving outside

o Inheritance/DNA

o Reproduction

 Asexual or sexual (exchanging genetic  


o Detecting and responding to environment

o Energy—all organisms need it, use it, and store


o Growth and Development

o Sustainability

 Homeostasis

o Evolution and Reproduction

 Evolve as a living organism

 Commonalities between “friends”

o Endosymbiosis

 One organism lives inside of the other

o What is symbiosis? Don't forget about the age old question of 11) Why are action potentials usually conducted in one direction?

 When two or more different species live together and  interact; they have a very close association with each other  It is not always beneficial!

o Associations

 Competition

 Two species interact but what they are doing is  

harmful to both of them

 We forced this in food production with the use of  pesticides, fertilizer, etc  stresses other species in  the area

what is food?

 75% of antibiotics = used by farmers 

 Niche: everything you need to live

 Combination of all abiotic and biotic needs of a  

species or population to survive and reproduce

 During a competition, some part of the niche is  


o “Friend” Relationships

 Exploitation

 One is harmed, one benefits

o Examples:

 Herbivores eat plants

 Predators kill other animals for food

 Parasiteslive in and on the organisms  


 They often cause harm

 Pathogens

 The average American is prescribed 17  

doses of antibiotics by the age of 20 

 Equivalent to 30,000lbs 

 Commensalism

 One species benefits and the other is unharmed/does not cost them

o Example: Barnacles on whales

 Mutualism

 Both species benefit  

 Survival and reproduction are both increased with  both species

 Microbiome:

 All organisms which live in symbiotic relationships  with humans

o Affects digestion/absorption, immune system,  

stress/psychological issues, development

 Have enzymes that digest substances we cannot  Communicate with our immune cells

 Amphibiosis:

 Transitions of one type of species-species interaction  to another

o Example: switching from commensalism to  


o This is based on population size and other  

present microbes

 Trophism:

 Movement of food from one organism to another

o Producers to consumers

 Food  

o It is an organic substance, meaning it is a hydrocarbon o Inorganic source = CO2

o Organic products are produced from inorganic sources by  organisms

 Who makes food and who eats food?

o Autotrophs: produce their own food

 Chemoautotrophs

 These are prokaryotes

 They transform light energy into chemical energy

 Photoautotrophs

 These are prokaryotes, protists, plants…. Or anything green or that has color and can make their own food  

from sunlight

o Heterotrophs: eat food produced by autotrophs humans are  heterotrophs

 Photoautotrophs

 These are prokaryotes

 Chemoautotrophs

 Can’t make their own food

 Rely on autotrophs to make food for us in the form of  sugar, which we then use to make other substances

 Humans, prokaryotes, plants, fungi, protists, animals   Prokaryotes

o Single celled organisms that have a simplistic structure and  function

 Include archaea

 Live in many extreme environments

 Include bacteria

 Live everywhere

o When they are pathogens, they can harm us

 Can be intracellular

 Enter into our cells and survive

o They produce a substance that causes harm

o They kill the cell that causes it to burst

 Apoptosis: cell death

 Can be extracellular

 They multiply outside

o Produce a substance that causes harm

o Cause an imbalance in our normal flora  


 Can be toxins

 Endotoxins

o Something structural that is there for a  

different purpose and unintentionally helps the  


 Example  lipopolysaccharide

 Exotoxins  

o Produce mainly as a defense

 Proteins

 Top disease-causing foodborne pathogen? 

 Viruses: 58% 

 Salmonella: 11% 

 Top hospitalizations? 

 Salmonella: 35% 

 Viruses: 26% 

 Top deaths? Salmonella: 28% 

 How to prevent foodborne illness:

 Cooking food properly (ie not prepping veggies and  

raw meat on same cutting board

 Salting

 Pickling

 Drying  

 Being clean

 Eukaryotes

o A cell that absorbed energy from another in the form of sugar  produced oxygen as a byproduct

o More mitochondria in muscle cells because they are the ones  that contain energy

o Protists

 Examples

 Algae

o They are photosynthetic

 Phytoplankton

 Zooplankton

o Plants

 Ferns

 Gymnosperms

 Angiosperms

 A flowering plant

 Mostly what we consume

 If it is green, it is a photoautotroph!

 Roots exist below the ground

o Circulatory system involves moving minerals  

and water to the photosynthetic cells

 Shoots exist above the ground

o Includes the leaves and stem cells

o Perform photosynthesis

 Uses sunlight and pigments

 Stomata (pores) of leaves allow CO2 in

 What we eat:

 Below ground vegetation

o Tubers, roots, and bulbs

 Above ground vegetation

o Leafy greens

o Fruit (this is really the ovaries of the plant)

o Fruit

 Flowers

 Production of flower attracts pollinators and then  

seed dispersal can occur  

 Most are hermaphroditic, meaning they have both  

male and female parts

o Male parts include a stamen, which has a  

filament that can project out of the flower and  

project the anther (contains the sperm pollen)

o Female parts are collectively referred to as the  


 Stigma: the top part that has a sticky  

substance that the pollen can stick to

 The sperm travels down the style, into  

the ovary, and then into the ovule, where

individual eggs are

 Different types of fruit

 Simple fruit

o From a flower that has one ovary, such as the  

pea fruit

 Aggregate fruit

o From one flower with multiple ovaries, such as  

a raspberry

 Multiple fruit

o From many flowers, such as a pinapple

 Photosynthesis

o To make food:

 Photosynthetic eukaryotes have specialized organelles  called chloroplasts

 Sunlight is needed

 Water and minerals come from roots

 CO2 is taken in through pores

 Pigments come from the chloroplasts

o Step 1: light reactions

 Photosystem

 Light energy is converted to electrical energy and  

then to chemical energy

o Photons, packets of energy, are measured in  

wavelengths and are part of the  

electromagnetic spectrum

 Antennae complex reaction center

 Arrangement of pigments

o Any substance that can absorb light energy

o Color is determined by wavelength it reflects

o Light is converted into heat, light, or chemical  


o The most important one is chlorophyll a

 Electron Transport Chain

 Lost electron is replaced

o H2O splits to produce O2 and H+

 ATP and NADPH are produced

 Electron from chlorophyll a is energized

 Energy carriers

 ATP has three groups of phosphates

o Tridi

 They receive, store, and deliver energy

 Electron carriers are NADH, FADH2, NADPH

 The first two pick up electrons and hydrogen atoms  

that have been released and NADPH deliver energy  

by providing electrons and hydrogen atoms

o Dark reactions

 Transforms chemical energy into food via the Calvin Cycle  4 steps

o Carbon fixation

 Remove carbon from CO2 by Rubisco  

(enzyme) and it is fixated to RuBP

o Energize sugar to incorporate it into existing  


o Sugar exits

o Recycle RuBP

 What type of relationship doesn’t exist within your microbiome? o Competitive  

 Fungi

o Decompose and release nutrients that would otherwise not be  available

 Can be single celled, like yeast, or multicellular

 These are chemoheterotrophs

o Metabolism

 Facultative: switch from oxygen-producing metabolism  Anaerobic cellular respiration = fermentation

 Fungi can live by either aerobic or anerobic cellular  


 Why do leaves turn colors in the fall? 

o Pigments are broken down which changes the light reflected  Animals

o Cells do not have a cell wall, which plant cells do have  Allows animals to have flexibility

o Invertebrates and vertebrates

o Mollusks

o Arthropods

o We consumed 200lbs/meat/person in 2014 

o What do we consume?

 Fish

 Both freshwater (trout) and saltwater (salmon)

 High in good fats

 Consider farm raised fish and overfishing

 Meat (land animals)

 High protein, bad fat

 Nutrition

o What element makes up most of your body weight?  

 Oxygen 

o What molecules are most prevalent in the human body? Oxygen,  carbon, hydrogen, nitrogen 

o Chemical building blocks of life

 Fats

 Phospholipids

 Triglycerides (aka cellulite, what we think of as “fat”)

o Three fatty acid molecules bonded to a glycerol


o Built from saturated fatty acids

o Fat tissue can be brown (converts chemical  

energy  heat) or white (storage)

o Lipolysis: fat cells break down triglycerides to  

release individual fats to produce ATP

 Cholesterol

o Both cholesterol and fats are hydrophobic

o Sterols

 Fats that have the same structure with  

different ingredients attached to them

 Contain four hydrocarbon rings fused  


o Hormones

o Anabolic steroid (resembles testosterone o Examples

 Eggs, shellfish

 Trans fat is the worst fat found in food, because it  affects blood cholesterol and consistently increases  bad cholesterol

 Saturated fats/fatty acids

o All carbon atoms in the hydrocarbon chain are  linked with a single covalent bond

o Solid at room temp

o You can stack them

o Examples

 Tropical fruits

 Animal products (meat)

 Unsaturated fats/fatty acid

o The beneficial form of fats that mainly come  from vegetables and fish 

o One or more atoms have a double bond, so  there is a kink preventing them from being able to lay flat

 Natural peanut butter with the oil on top  is due to the kinks, whereas  

hydrogenation of peanut butter makes it  

consistently smooth

o Examples

 Veggies

 fish

 Functions:

o Make up membranes of cells

o Signals within cells

 Can act as hormones

o Provide body heat

o Provide insulation and cushioning

 Problems with food labels:

o If a product has less than 0.5g trans  

fat/serving, it is allowed to be listed as “0”

o So a reduced serving size allows companies to  put 0g trans fat

o Look at ingredients to determine if there is  transfat

 Sodium

 It is an ion with a charge, usually found as an  additive

 Carbohydrates

 Monomers, individual units of a macromolecule  Polymers, chains of monomers bonded together o Include carbohydrates, proteins, and nucleic  acids

o How to build:

 Dehydration synthesis:

 Remove water molecules so  

monomers can bond

o How to break:

 Hydrolysis

 Add water, breaking apart  


 Cellulose is the most common carbohydrate on earth  Food label: Listed as sugars and fibers

o 15g sugars, 5g fiber, but total carbs = 25 g

 5g that are missing = starch  glucose

o Not all carbs are sugars but all sugars are carbs  Monosaccharides

 Glucose and fructose

 Love water

 Disaccharides

 Sucrose formed through  

dehydration synthesis

 Glucose and fructose are bonded

 Polysaccharides

 On food label is listed as fiber

 Monomers are linked together in  

different ways

o Glycogen is a storage molecule

o Chitin is produced in fungi and invertebrates  for structure

 Proteins

 Built from amino acids— there are 20 different ones  Make you who you are

 Storage

o Energy (contribute 4cal/g)

 Structure

o Cytoskeleton = scaffolding of cells

o Defines function

o The sequence of amino acids is their structure

 This is 3-D

o The folding determines their function

 Transport:

o Blood cholesterol

 High density lipoproteins (HDL)

 Bring fats home to the liver while  

LDL does its job

 Low density lipoproteins (LDL)

 Brings fats to cells

 Contain a lot of cholesterol,  

phospholipids, and a lot of fat

 Saturated fats keep both of these high,  

while unsaturated fats keep HDL high  

and LDL low

o Channel proteins: tunnels in cells that allow  specific substances in and out

o Carrier proteins: move to bring a substance in  or out of cell

 Catalysis

o Speed up reactions, by way of enzymes

 Defense

o Antibodies are produced to defend against  specific invaders

 Communication

o Insulin and glucagon regulate blood sugar

o Leptin and grelin regulate appetite

 Gene regulation

o Transcription factors turn the gene on or off o Can be influenced by diet

 Denaturation

o Destruction of the 3D shape by heating them  up, changing the pH or making it very acidic,  

increasing the salt concentration

 Nucleic acids

 Nucleotides are the building blocks of hereditary  material

 DNA is turned on and  RNA produces proteins  Vitamins

 Take vitamins after a meal so that you can break  down the substance 

 Needed in tiny amounts

 Organic molecules

o Fat soluble

 Can get locked up in fat stores

o Water soluble

 Can consume at high rates and is okay in

short term

 Most common vitamin deficiency in US: B6 

 Vitamin D is the only one that human can synthesize  but people still don’t get enough

 Minerals

 Highest mineral deficiency is iron 

 We need trace minerals

 The ones we need come in the form of ions

 Iodine is critical for metabolism

o From salt and seafood

 Fluoride for teeth

 Cobalt

 Digestion

o GMOs

 We don’t have to label GMOs

 Drug production

 Food production

 Curing genetic disease

 Sugar Beets have the highest percentage of genetically  engineered crops in the US 

 Roundup prevents plants from making an essential amino  acid

 A gene inserted into a plant makes it produce its own insecticide, and doesn’t really effect farmers as much

because they produce more crop

o We have to break food down in order to digest it and utilize the  nutrients

o Ingestion, digestion, absorption, elimination

 Ingestion

 Animals are consumers, so we eat other organisms in some way or another

 Digestion

 We break down the consumed organism

 Absorption

 Outside the cell we consume monosacharides,  

disaccharides, etc.

o As we consume proteins we must degrade  


 We absorb the vitamins and minerals

 Enzymatic reactions

o Reactant undergoes some sort of change that makes it become a product (and produces ATP as well)

 This process or change requires activation energy o Enzymes are biological catalysts

 Without them, reaction time would be way too slow—  enzymes lower the activation energy needed and therefore increase the speed of the reaction

 This could be one million times the actual rate of the  reaction

o Structure of enzymes:

 3D shape determines the function

 There is an active site within the enzyme

 A substrate binds to this site

o Substrate ~ reactant in a typical chemical  


o If you require a substrate, this means that an  

enzyme is involved

o Anabolic Reaction

 Enzyme has an induced fit and it can store energy for later  use

o Catabolic Reaction

 There is a big substrate that docks into a different type of  enzyme, which causes it to change shape through different processes

 Involves breaking down energy for current use

o Metabolism:

 A  (enzyme 1)  B  (enzyme 2)  C  (enzyme 3)  D  If enzyme 2 isn’t formed properly, what is the result? o Increase in Product B 

 A  (enzyme 1)  B  (enzyme 2)  C  (enzyme 3)  D  What is enzyme 3’s substrate? 

o C 

 A  (enzyme 1)  B  (enzyme 2)  C  (enzyme 3)  D  What enzyme is directly responsible for the  

production of D? 

o Enzyme 3 

 CO2 + H2O  glucose

 Glucose  glycogen

o Endergonic reaction series (storing energy)

 Anabolic: building up something big,  

happens during photosynthesis

 Makes monomers into polymers  

during dehydration synthesis

 Break down glycogen by adding water through hydrolysis  This makes it a catabolic reaction  cellular  


o AKA exergonic reaction

 Metabolic pathways in the body involve several reactions  and there are several intermediates, each one of which has its own enzyme

 Food Processing

o Enhancing colors

 For example, farm-raised salmon has food coloring added  to it

 It naturally is not pink because it is not eating the  

natural things that make it turn pink

o Augment the flavors

 Hydrogenated oils are trans fats

 Hydrolyzed food products are added to foods to make them tasty

 Sweet, sour, bitter, salty, umami

o ***Smell is essential for taste!***

o Extend shelf life by using preservatives

 GRAS substances: “generally recognized as safe  


 Old techniques include smoking, salting, drying, freezing,  sugaring

o Improve texture by adding trans fats

o Reduce calories by removing trans fat

o High Fructose Corn Syrup

 Naturally occurring carbohydrates are digested to create  fructose

 You need less, so it ends up being cheaper

 Food Labels

o Organic vs. natural

 You can have an organic product that isn’t natural

 Organic:

 Grown and processed using organic farming methods that recycle resources and promote biodiversity

 Crops grown without synthetic pesticides,  

bioengineered genes, petroleum based fertilizers,  

and sewage sludge based fertilizers

 Natural:

 Can’t be highly processed

 More regulated in poultry and meat industry

 Adding heat to a system

o Denatures proteins

o The vitamins can also degrade

o Burning (ie. Grilling) causes carcinogens to form

 Which structure does not digest to absorb nutrients?

o Esophagus 

 Mouth:

o Chemical: salivary amylase, mucus

o Physical: smell/taste, tongue, teeth, hard/soft palate o Digestion: starch

o Absorption: glucose

 Esophagus:

o Chemical: no enzymes, mucus

o Physical: smooth muscle peristalsis

 Sphincters (upper and lower)

 Epiglottis: shuts off respiratory system from throat to  prevent food from going into respiratory system

o Digestion: none

o Absorption: none

 Stomach:

o Chemical: HCL (acid), denatures protein

 Pepsin (enzyme in stomach) can chew it up, mucus  

(protects stomach lining)

o Physical: rugae— folds that churn the food, allowing for more  efficient digestion, phonic sphincter

o Digestion: breaking down proteins

o Absorption: amino acids and alcohol

 You only get about 10% of nutrients here

 Pancreas:

o Chemical: enzymes lipases, carbohydrates, proteases  These all get sent to the small intestine

o Physical: n/a

o Digestion: n/a

o Absorption: about 80%

 Small Intestine:

o Which of the following reasons explains why starch molecules  must be broken down before they can be absorbed by the small  intestine? 

 They are too large to pass through the plasma membrane  of the intestinal cells 

o All ingredients from pancreas as well as mucus

o Chemical: n/a

o Physical: n/a

o Digestion: fats, proteins, carbs

o Absorption: amino acids, fatty acids, cholesterol,  

monosaccharides, minerals, vitamins

 Liver/Gall Bladder:

o Makes bile

o Goes around food and pulls apart fats, allows lipases to “get in  there and chew them out”

o Chemical: n/a

o Physical: n/a

o Digestion: n/a

o Absorption: n/a

 Large Intestine:

o Chemical: mucus

o Physical: villi, microvilli

o Digestion: not much

o Absorption: water, vitamins, minerals (due to mutualistic bacteria that live there)

 Fiber-rich food: will absorb more sacccharides

 An organism who can create organic substances from carbon dioxide  by chemical energy is considered: 

o A chemoautotroph

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