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Lecture 1

BIOL 103 Lecture Notes - Lecture 1: Udder, Eating Animals, Lysosome

Course Code
BIOL 103
Virginia K Walker

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Biology 103 Week 1 Notes
Autotrophs: organisms that harvest light or chemical energy and store it in carbon
compounds, exist in inorganic environments and manufacture organic compounds,
primary producers,self nutrition, ex: plants
Heterotrophs: organisms that get complex nutrients from the environment and are
found at higher trophic levels, receive nutrition by eating other organisms, other
nutrition, ex: humans
Types of Heterotrophs
Bulk Feeders
Eat relatively large pieces of food
Example: humans
Fluid Feeders
Suck nutrient-rich fluid from a living host
Example: mosquito
Substrate Feeders
Live in or on their food source
Example: maggots, burrow themselves in animal carcasses
Suspension Feeders
Eat small organisms or food particles suspended in the water
Example: clams and oysters
Filter Feeders
Move water through a filtering structure to obtain food
Example: humpback whale
Intracellular Digestion: hydrolysis of food inside vacuoles, food or liquid is engulfed by a
cell by phagocytosis or pinocytosis, the vacuoles containing food then fuse with
lysosomes that contain enzymes that digest the food in a safe compartment enclosed
by a protective membrane, example: sponges
Extracellular Digestion: digested food products are phagocytosed directly into the cells
that line the gastrovascular cavity - further digested intracellularly, waste is excreted
out of the mouth (simple body plans, gastrovascular cavity i.e hydras) or the anus
(alimentary canal, i.e humans)
Fungi can get nutrients from both dead organic matter and living animals (act as
parasites), use extracellular digestion … meaning they can be both parasitic or

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Athlete’s foot fungus - extends fungal branches (hyphae) into the cells
Dactylella dreschsleri - a fungus that has sticky knobs along the hyphae that can hold
nematode worms, hyphae penetrate the worm’s body and digestive enzymes are
released and extracellular digestion occurs
Arthrobotrys dactyloides - a fungus that makes traps that are used to capture nematode
worms, nematodes enter the traps made by three cells and the cells swell and constrict,
lassoing the worm, then the hyphae penetrate the worm and extracellular digestion
takes place
In phagocytosis there are various proteins (including SNARES), including Ca++ that are
involved, complicated process in protozoans
Humans protect themselves from microbes with phagocytosis, however there are some
microbes (i.e. streptococcus) that have evolved mechanisms to try and escape
Streptococcus eventually make antibodies (y) a(er a couple of weeks

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Parts of the digestive system:
Tongue - pushing the food around while you chew with your teeth, when you're ready
to swallow, the tongue pushes a tiny bit of mushed-up food called a bolus toward the
back of your throat and into the opening of your esophagus, the second part of the
digestive tract!
Oral cavity - this entire structure is also called the mouth; the structures within the
mouth allow us to taste and masticate (chew) food, to swallow food and drink, and to
manipulate the air that comes up from the voice box so that we can form words!
Salivary glands - produce saliva, which keeps the mouth and other parts of the digestive
system moist, it also helps break down carbohydrates (with salivary amylase, formerly
known as ptyalin) and lubricates the passage of food down from the pharynx to the
esophagus to the stomach!
Pharynx - this muscular tube, which is lined with mucous membranes is a passage that
connects the back of the mouth and the nose to the esophagus
Esophagus - functions as the conduit for food and liquids that have been swallowed
into the pharynx to reach the stomach!
Gall bladder - holds bile produced in the liver until it is needed for digesting fatty foods
in the duodenum of the small intestine !
Pancreas - a digestive exocrine gland and a hormone-producing endocrine gland,
functioning as an exocrine gland, the pancreas excretes enzymes to break down the
proteins, lipids, carbohydrates, and nucleic acids in food, functioning as an endocrine
gland, the pancreas secretes the hormones insulin and glucagon)to control blood sugar
levels throughout the day!
Small intestine - absorbs about 90% of the nutrients from the food we eat!
Large intestine - the final section of the gastrointestinal tract that performs the vital
task of absorbing water and vitamins while converting digested food into feces!
Rectum - final segment of the large intestine that connects the colon to the anus, it
stores fecal matter produced in the colon until the body is ready to eliminate the waste
through the process of defecation
Anus - the final segment of the gastrointestinal tract, it acts as the orifice that feces
pass through during defecation!
Pyloric Sphincter - a band of smooth muscle at the junction between the pylorus of the
stomach and the duodenum of the small intestine, it plays an important role in
digestion, where it acts as a valve to controls the flow of partially digested food from
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