Unit 2: Cells, Tissues, And Organisms

Prokaryotic cells

• Lacks a membrane-surrounded nucleus

  • have a nucleoid

endosymbiont theory

A host cell engulfed a prokaryote, which evolved into the mitochondria, thereby becoming the eukaryote. Later on, it engulfed a photosynthetic prokaryote, which became the chloroplast.

why is a high surface to volume ratio important

It is important becase a high ratio allows for more effcient exchange of materials

origins for mitochondria

Aerobic (oxygen using) nonphotosynthetic prokaryotes

origins of chloroplasts

photosynthetic prokaryotes

Evidence fort the endosybiont theory

• Mitochondria and chloroplasts have 2 membranes bound around them

• Both contain their own circular DNA and ribosomes

• reproduce independently by binary fission (asexual reproduction)

surface area to volume ratio

SA / V

what materials must pass across a cell’s membrane

• oxygen:

  • for cellular respiration

• carbon dioxide

  • as a waste product

• water:

  • for maintaining cell volume and fluid balance

organization unit of life

The cell

Nucleus

Control cente of the cell: houses DNA, controls cell growth, metabolism, and reproduction.

• plant cells, animal cells

Nucleolus

production and assembly of ribosomes

• plant cells, animal cells

Cell Wall

Maintains the cell’s structure and rigidity

It is fully permeable to water because its material creates pores

• plant cells: cellulose, chitin (fungi)

• prokaryotes: peptidoglycan

nuclear envelope and pores

Envelops the nucleus and controls what goes in or out

• plant cell, animal cell

Rough Endoplasmic Reticulum (RER)

membranes that house ribosomes that produce proteins that will be secreated out of the cell

• plant and animal cells

Smooth endoplasmic reticulum (SER)

lipid synthesis, detoxification, calcium storage

• plant and animal cells

Ribosomes

Protein synthesis (translation)

• plant and animal cells

• prokaryotes

Golgi Apparatus

Cellular postoffice: modifies, sorts, and packages proteins and lipids into vesicles to be shiped

• plant and animal cells

lysosomes

cellular digestion - macromolecules are

hydrolyzed here

• animal cell

Central Vaculole

Stores water, nutrients, and waste

• plant cell

Mitochondria

powerhouse of the cell, creates ATP via cellular aeirobic respiration

• plant and animal cell

Chloroplast

conduct phtosynthesis to create glucose that will power the cell

• plant cells

peroxisomes

detoxicification and metabolism

• Plant and animal cells

Microtubules

Maintains the cell’s shape and structure, forms mitotic spindles for division, and forms intracellular highways

• plant and animal cells

microfilaments

maintain cell structure and allow the cell to have ameboid movement

• plant and animal cells

cilia and flagella

locomotion and sensory processing

• cilia: animal cell

• flagellum animal cell, prokaryote

free floating ribosomes Vs RER ribosomes

Free floating ribosomes create proteins that will stay in the cell

RER ribosomes will go outside of the cell

endomembrane system

It is a network of organelles that work together to prepare and transport lipids and proteins pout of the cell

Key organelles in the endomembrane system

• nuclear envelope

• the endoplasmic reticulum,

• Golgi apparatus

• lysosomes,

• various kinds of vesicles and vacuoles

• the plasma membrane.

pathway of synthesis of a protein destined to be secreted from the cell synthesis

RER ribosomes produce proteins that are packaged into transport vesicles

they travels to the Golgi apparatus’ cis face for further processing and sorting, and then exits the Golgi’s trans face in secretory vesicles to be released from the cell via exocytosis at the plasma membrane

plasmodesmata

microscopic channels that directly connecting the cytoplasm of adjacent plant cells and enabling intercellular communication and the transport of molecules

Plasma membrane

selectively permeable, controlling the movement of substances into and out of the cell

ECM

an intricate network composed of an array of multi domain macromolecules organized in a cell

• creates structural support

• cell signalling

Plant and Animal cell key differences

• cell wall (PC)

• Chloroplasts (PC)

• Central Vacuole (PC)

• Rectangulaar Structure Vs Irregular shape

• Lysosomes (AC)

fluid mosaic model

refers to the flowing nature of the phospholipids along with the proteins embedded within it

• enables

  • transport

  • signaling

  • cell growth

  • division

How fast and in what orientation do lipids move within a membrane

They move side to side in a wave, and it takes them 1 second.

Unsaturated versus saturated hydrocarbon tails.

Saturated = viscous: phospholibids are all packed tightly together bc fatty acid tails are straight

Unsaturated = fluid: phospolipid tails have kinks so there’s gaps

Cholesterol within the animal cell membrane

Acts as smth that maintains the homeostasis of the membrane

• reduces membrane fluidity at moderate temperatures by reducing phospholipid

• increase membrane fluidity at low temperatures by hindering solidification by disrupting the regular packing of phospholipids

what is the role of carbohydrates in the cell membrane

cell recognition and communication, acting as unique molecular identifiers on the cell surface

difference between integral and peripheral proteins

• Integral proteins extend through the whole membrane

• peripheral proteins only extend halfway or not at all in the membrane

how can some nonpolar molecules pass easily through the phospholipid bilayer

NP molecules aren’t repelled by the polare hydrophilic heads of the phosopholipids

aquaporins

facilitates the movement of water across the membrane

passive transport

when molecules move across the membrane from areas of high concentration to areas of low concentration

• facilitated transport: this happens with the help of a protein channel

• passive transport: molecules diffuse directly through the membrane

active transport

molescules are moved low to high (against concentration gradient) using ATP

diffusion

movement of molecules from a area of high concentration to a area of low concentration

Osmosis

The process of water moving to an area of low water, high solute, and leaving an area of high water, low solute

• Osmotic activity depends on the solute concentration

• More solute, more osmotic pressure, more water enters

hypertonic

there is more solute outside then inside the cell. cell will lose water and shrivel

hypotonic

there is less solute outside the cell then inside the cell. cell will gain too much water and lyse

isotonic

there is equal concentration of solute outside and inside the cell. water will diffuese in and out at the same rate

gated channel proteins

membrane proteins that controls what Ions go accross the membrane with a specific signal

sodium potassium pump

3 Na in 2 K out

• powered by ATP

membrane potential

difference in electrical voltage across a cell's membrane, created by moving ions against their concentration gradient

cotransport

when the movement of one substance down its concentration gradient provides the energy for the other substance against the concentration gradient

tissues

collection of similar cells that are orgainzed to have a specific function

organs

group of tissues that combine to perform a specifc, specialized functions

Organ

organ systems

a group of organs that work together to perform a specific life process

interstitial fluids

liquid that is between cells

Areolar tissue

• Loose connective tissue

Provides support, helps protect organs, binds skin together, and gives it elastic properties, found in the digestive and respiratory systems

Adipose Tissue

Loose connective tissue

found throughout the body, stores lipids , insulation, protection, and long term energy

dense irregular connective tissue

Function: able to withstand tension exerted in many directions; provides structural strength

Location: dermis of the skin;

Neurons - nervous tissue

found in the brain, spinal cord, and nerves, allows for cells to communicate