BIO 190 Ch#4 *Evolutionary Origin of Cells and their General Functions*

The origin of life can be viewed as a process consisting of what 4 overlapping steps

1. nucleotides and amino acids were produced first

2. polymers formed RNA and/or DNA, proteins

3. Polymers became enclosed in membranes

4. Polymers enclosed in membranes developed a function

prebiotic soup

"before life" organic molecules accumulated in the oceans

organic molecule

a molecule containing at lease one C-H bond and a molecules that energy can be extracted from to do work on another process

all biological molecules are

organic

what does the extraterrestrial hypothesis propose

that the organic molecules present in the meteorites, asteroids and comets reached the surface of Earth through collisions

what does the deep-sea vent hypothesis propose

that key organic molecules may have originated at deep-sea vents, where super heated water containing many dissolved gases and metal ions mixes with cold seawater

Experimental evidence supports the hypotheses that polymers may have formed on____________________________

clay surfaces or in the prebiotic soup

Protobionts are envisioned as possible precursors of living cells given what characteristics

1. A boundary separated internal contents from the external environment

2. Polymers inside the protobiont contained information

3. Polymers inside the protobiont had catalytic function

4. Protobionts eventually developed the capability to self-replicate

what may have been the first molecule found in protobionts

RNA

what are catalytic RNA molecules

ribozymes

what is the RNA world

a hypothetical period on early Earth when both the information needed for life and the catalytic activity of living cells were contained in RNA molecules

describe the stability of DNA vs RNA

DNA is stable for lots of years whereas RNA is only stable for a minute or so

what is the primary difference between a living cell and a protobiont

a living cell undergoes precise self replication whereas a protobiont uses prebiotically created monomers

why are cells small

cells can not have a large volume because they would not be able to diffuse in and out fast enough "nutrient waste exchange"

describe the surface area vs volume of a cell

large surface area/ small volume

name 4 things shared by eukaryotes, plants, and bacteria

DNA, plasma membrane, ribosomes, cytoplasm

site of metabolism

cytoplasm

what synthesizes polypeptides

ribosomes

what allows bacteria to attach to surfaces and to eachother

pilli

allow certain bacteria to swim

flagella

what is a structure shared by bacteria and animal cells

flagella

site where DNA is found

nucleotide

encloses the cytoplasm

plasma membrane

eukaryotic cells exhibit extensive...

compartmentalization

dividing the cell into “rooms” (compartments)

Each "room" = an organelle, like the nucleus, mitochondria, or Golgi apparatus

an organelle is a

functional unit (like a ribosome)

what is a prokaryote vs eukaryote

Prokaryote:

No nucleus – DNA floats freely in the cytoplasm.

No membrane-bound organelles (like mitochondria or ER).

Usually smaller and simpler.

Found in bacteria and archaea.

Eukaryote:

Has a nucleus – DNA is enclosed in a membrane.

Has membrane-bound organelles (e.g., mitochondria, ER, Golgi).

Usually larger and more complex.

Found in plants, animals, fungi, and protists.

if all cells have the same dna how do they display different features

all cells have the same genome but each cells "scrolls through" the genes to function differently

ex: long hair on head but short hair on arms

genome

all of an organism's genetic material

each of your cells contains the same genome but makes its own ________

proteome

what is a proteome

The full range of proteins produced by the genome

when looking at 3 different human cell types, what would you say is the same vs what is different

genomes- do not differ

proteomes- differ

what is found in a plant cell that is not found in animal cells

chloroplasts, central vacuole, cell wall

Think of Bacteria, Animal Cells and Plant cells: where is mitochondria present

in animal and plant

Think of Bacteria, Animal Cells and Plant cells: where are ribosomes present

in all

Think of Bacteria, Animal Cells and Plant cells: where is cytoplasm present

present in all

bacteria- in a side compartment in the plasma membrane

animal and plant- composed of membrane bound organelles surrounded by cytosol

Think of Bacteria, Animal Cells and Plant cells: where is a cell wall

bacteria and plant

not animals

Think of Bacteria, Animal Cells and Plant cells: where is flagella present

bacteria and animal, not plants

a eukaryotic cell can be viewed as a system of what 4 interacting parts

1. Nucleus

2. Cytosol:

3. Endomembrane System

4. Semiautonomous organelles

describe the nucleus ? what does it contain and what is the location of

contains chromatin, nucleolus, DNA and chromosomes location of most genome, gene regulation

describe cytosols location and role

located outside of the cell organelles but inside the plasma membrane

central coordinator for many metabolic activities, both catabolic and anabolic reactions occur here

What is part of the endomembrane system

nuclear envelope, ER, golgi apparatus, lysosomes, vacuoles, peroxisomes, plasma membrane

memory tip: LVEGAN-PPM

lysosomes, vacuoles,ER, golgi apparatus, nuclear envelope *NOT NUCLEUS*, peroxisomes, plasma membrane

role of nuclear envelope

double membrane that surrounds the nucleus

role of the ER

protein secretion and sorting

role of the golgi appartus

protein secretion, packaging and sorting

role of peroxisomes

breakdown of toxic molecules, breakdown and synthesis of organic molecules

role of plasma membrane

cell signaling, adhesion, uptake and excretion of ions and molecules

what is the site of protein synthesis

ribosomes

the cytoskeleton is the network of what 3 different protein filaments

1. microtubule

2. intermediate filaments

3. actin filaments

what is the general function of microtubules

rigid hallow tubes used during cell division and to move proteins through the cytoplasm

what is the general function of actin filaments

microfilaments that are the smallest cytoskeleton filaments and are important for muscle contraction

what is the general function of intermediate filaments

tough fibers that give strength to cells and connect cells to each other, rope like structure, helps the ECM

cytoskeleton allows for what type of movement

whole cell, internal movement, and exterior movement

describe internal movement of the cytoskeleton

motor proteins "walks" on microtubules and actin filaments

describe exterior motion in cytoskeletons

clear away from harmful particles

the membranes in the endomembrane system are made of what

a phospholipid bilayer made in the smooth ER

lipids made in the smooth ER flow to ......

the nuclear envelople

What is the Nucelar envelope?

double membrane enclosing the nucleus

nuclear pores

openings across the nuclear envelope that are formed by proteins of the nuclear pore complex

Where are chromosomes found?

nucleus of a cell

what are chromosomes formed of

chromatin

what is the region of ribosomes assembly (synthesis)

nucleolus

what happens when ribosomes attach to the rough ER

they make protein by reading RNA, the protein causes the folding

rough ER

studded with proteins and its functions include protein sorting, glycolisatation and insertion of membrane proteins

smooth ER

lacks ribosomes. functions: metabolism, detoxification, calcium storage and making lipids (lipid synthesis)

what does the golgi apparatus do

directs processing, sorting, and secretion of cellular molecules

rough ER makes the protein but transports it to ...

the golgi aparatus

lysosomes

break down macromolecules

peroxisomes

neutralize byproducts of chemical reactions

vacuoles

compartments that contain fluid or solid substances

central vacuole

in plant cells it provides storage and structure, stores excess waste

mitochondria and chloroplasts are considered...

semiautonomous "kinda independent"

Enzymes in lysosomes are responsible for what

breaking down and recycling various materials inside the cell.

what does the mitochondria do

synthesize (make) ATP

function of the chloroplast

photosynthesis

what does the centrosome do ?

makes microtubules and contains centrioles

researchers are looking at small organelle that has a particular function. they notice that this organelle breaks down carbohydrates, lipids, proteins, and nucleic acids. which organelle are they looking at?

lysosome - lysosomes break down macromolecules and carbohydrates, lipids, nucleic acids and proteins are macromolecules

remember peroxisomes break down harmful substances like -OH

Bacteria Cell, Animal Cell, Plant Cells: which have a cell wall

bacteria and plant

Bacteria Cell, Animal Cell, Plant Cells: which have flagella

bacteria and Animal (sperm)

Bacteria Cell, Animal Cell, Plant Cells: which have a plasma membrane

all of them

Bacteria Cell, Animal Cell, Plant Cells: which have a cytoplasm

all of them

Bacteria Cell, Animal Cell, Plant Cells: which have a ribosome

all of them

Bacteria Cell, Animal Cell, Plant Cells: which have a chromosome

all of them

Bacteria Cell, Animal Cell, Plant Cells: which have a endomembrane system

plants and animals, not bacteria

Bacteria Cell, Animal Cell, Plant Cells: which have mitochondria

all BUT bacteria

Bacteria Cell, Animal Cell, Plant Cells: which chloroplast

only plant cells

describe whole cell movement of cytoskeleton

flagella, cilia

are the intermediate filaments the smallest filaments

no, actin is the smallest

What 4 things does the nucleus contain

nuclear envelope, nuclear pore, nucleolus, chromatin

what is chromatin

complex DNA and proteins

cotranslational protein sorting vs post- translational protein sorting

cotranslational- at the same time

post- after protein synthesis

when would a protein complete its sorting without a sorting signal

in the cytosol

a researcher is looking at protein sorting, he notices that the protein stops synthesizing in the ER completely where would this mutation be

in the ribosome

what components are used during protein sorting

ribosome, mRNA, cytosol, ER

researchers are looking at a ribosome who is protein sorting, they notice the ribosome pauses translation of the mRNA and goes toward the ER where it continues to translate the mRNA, which type of sorting is this

cotranslational

Co-translational sorting = the ribosome moves to the ER during translation, guided by a signal peptide, and completes translation while the protein enters the ER.

descirbe the 3 types of protein sorting

Cytosolic Synthesis- occurs in Cytosol, No sorting needed

goes to Cytosol

Co-Translational: Starts in cytosol → ER, sorting happens During translation, goes to ER, Golgi, membrane, lysosome

Post-Translational: occurs in Cytosol, sorting occurs After translation finishes, goes to Nucleus, mitochondria, etc.

what is the extracellular matrix composed of

protiens and pollysaccharides

functions of the extracellular matrix

strength, structural support, organization, cell signaling

what 2 components bring structural support to the ECM

collagen and elastin