Unit 2: CellsStudy Guide

I. Organelles

Organelles in cells are similar to the organs in our bodies. Each organelle has an important job to do to help the cell function correctly. It helps if you imagine the cell as a small product-producing factory with each organelle as a different department. Organelles are only found in Eukaryotic cells.

Cell membrane - Selectively permeable barrier controls what enters and leaves the cell. Important for cell transport

Nucleus -Contains DNA and RNA and controls cell functions

Nucleolus - Makes ribosomes. Located within the nucleus. Ribosomes – Make Proteins. Located either in the cytoplasm or on the Rough ER Cytoplasm - the nutrient-rich fluid that fills the cell and surrounds the organelles Rough Endoplasmic Reticulum – network of membranes, covered in ribosomes that

make proteins Smooth Endoplasmic Reticulum - a network of membranes, without ribosomes,

that make lipids Golgi Apparatus – Packages and transports products from the ER into vesicles Vesicles – spherical membranes in which the cell transports products or wastes Vacuole –a special vesicle for holding water and nutrients and water for the cell.

Plant’s vacuoles are very large. Mitochondria - a kidney-shaped organelle with an interior membrane. The site of ATP

synthesis and cell respiration, mitochondria contain their own set of DNA and are thought to be ancient bacteria acquired by the cell.

Chloroplast – Found in plant cells (and some protists) chloroplasts are full of a pigment known as chlorophyll and the site of photosynthesis.

Centrioles - the two centrioles, together known as the centrosome, aid in cell division in animal cells.

Cilia

Cytoplasm

II. Cell Transport A. Cell

Transport is the process of how substances move into and out of cells through a semi-permeable cell membrane.

B. There are two major types of transport:a. Passive Transport

i. Does not require energyii. Moves substances down the concentration gradient (high concentration low concentration)

b. Active Transporti. Requires energy in the form of ATP

ii. Moves substances against the concentration gradient (low concentration high concentrtion) C. Diffusion:

a. The movement of solutes from high concentration to low concentrationb. Substances pass directly through the cell membranec. A form of passive transport

D. Osmosis a. The diffusion of water b. Water passes directly through the cell membranec. A form of passive transport

E. Facilitated Diffusiona. The movement of large or polar molecules from high concentration to low concentrationb. Must pass through special protein channels in the cell membranec. A form of passive transport

F. Tonicitya. A comparison of the concentration of solutes in two solutions.b. A solution is hypertonic when it has more solutes than another (think hyper kids have MORE energy)c. A solution is hypotonic when it has fewer solutes than another (think hypothermia = low body temp)d. A solution is isotonic when it has the same amount of solutes than another one.

G. Equilibrium a. Cell transport stops once a system has reached equilibrium. The concentrations of materials are the

same on either side of the membrane.

Vesicles

LysosomeCytoskeleton

III. Six Kingdoms

a. Kingdom Archeabacteria – i. prokaryotes that live in extreme environments.

ii. They are unicellulariii. They live in extreme environments, like volcanoes and deep-ocean trenchesiv. Prokaryoticv. They are chemoautotrophs – use chemicals in their environment to make their own

foodvi. Independent evolutionary history

b. Kingdom Eubacteria – i. Prokaryotes that are everywhere!

ii. They are unicellulariii. Prokaryoticiv. Live in every habitat on earthv. Some are beneficial, like in our yogurt or stomach

vi. Some cause disease, like Salmonella and E. coli

c. Kingdom Protista – i. eukaryotes that are very diverse and is like the “junk drawer” kingdom

ii. Eukaryoticiii. Unicellular or multicellulariv. Reproduce sexually or asexuallyv. Autotrophs or heterotrophs

vi. Includes algae, protozoa, slime molds

d. Kingdom Fungi i. eukaryotes that absorb their nutrients

ii. Eukaryoticiii. Unicellular or multicellulariv. They are decomposers – break down waste and dead stuffv. Reproduce sexually or asexually

vi. Consume food through absorption – only kingdom that does this.

e. Kingdom Plantae i. Eukaryotes that make their own food

ii. Eukaryoticiii. Autotrophs – make own food through photosynthesis!iv. Multicelluarv. Reproduce sexually or asexuallyi. Includes trees, flowering plants, mosses, ferns, green algae, grasses, vines, etc.

f. Kingdom Animalia i. Eukaryotes that consume their food

ii. Eukaryoticiii. Multicelluariv. Heterotrophs – consume foodv. Reproduce sexually or asexuallyi. From sponges to penguins!

V. Viruses A. A virus is an infectious particle made only of a piece of DNA or RNA surrounded by a protein coat.

i. Very small and needs a host to do anythingii. Shaped like spirals or soccer balls (ex: Ebola, Aids, the Flu, West Nile, Chikungunya)

B. Reproduce differently from eukaryotic and prokaryotic organisms:i. Virus invades the cell

ii. Virus takes over cell activities to make more copies iii. Exocytosis (new viruses burst out of the host cell,

destroying it)C. Nucleic Acid – Can either be DNA or RNA that contains the virus’s

genes. D. Protein Coat – Sometimes called a capsid, protects the virus as it

travels to a new cell to invade. E. Two main processes in which new viruses can be made:

i. Lytic cycle1. New viruses lyse the cell, killing it

ii. Lysogenic cycle1. The viral DNA gets included into the host DNA2. When the host cell replicates, it copies the viral

DNA too!3. At a certain point it enters a lytic phase and the viruses break out of the cell,

killing it. F. Viruses are non-living. They do not need food or energy in order to survive.G. Viral RNA or DNA can change and evolve over time

i. Viruses cannot respond to stimuli in the traditional sense, but they can mutate over time. Some of these mutations are beneficial for them.

VI. Photosynthesis

b. Definitioni. Process that takes sun energy, carbon dioxide and water to make glucose!

c. Formulai. Sun + water + carbon dioxide Glucose + Oxygen

ii. Sun + 6 H2O + 6 CO2 C6H12O6 + 6 O2

REACTANTS PRODUCTSd. Takes place in chloroplast (organelle in plants)e. Creates glucose, a sugar, which can then be used in cell respiration

vi.vii.

viii.ix. VII. Cellular Respirationx.

a. Definitioni. The break down of glucose into 38 ATP for cell energy

b. Formulai. Glucose + oxygen carbon dioxide + water + ATP

ii. C6H12O6 + O2 6 CO2 + 6 H20 + 36 ATP! REACTANTS PRODUCTS

c. Occurs in the mitochondria (organelle – “powerhouse”)

Cell Respiration Diagram

d. Occurs in 3 main stepsi. Glycolysis – occurs in the cytoplasm. Glucose molecule is broken down to make 2

ATP.ii. Kreb’s Cycle – occurs in the mitochondria. Cycle of reactions that makes 2 ATP.

iii. Electron Transport Chain – occurs in the mitochondria. Final stage where 34 ATP are made.

e. ATP(adenosine triphosphate)

i. ATP supplies you with energy to carry out everyday functions

ii. Has three phosphate groups – when the third phosphate is removed, energy is

released. iii. When third phosphate is removed, ATP becomes ADP (adenosine diphosphate).

VIII. MitosisThe cell cycle refers to the life cycle of a Eukaryotic cell. At any given time body cells are in one of two

different phases of their lives:

A. Interphase: makes up 90% of the life of a cell. This is the phase where the cell is growing, carrying out normal functions, and duplicating its genetic material. There are three stages of interphase:

1. G1 Phase – The cell is growing.2. S Phase – Synthesis phase.  Here, the DNA is replicating3. G2 Phase – In this phase, the cell is double-checking to make sure there were no errors made when copying the DNA

B. Mitosis:  A very short part of the cell cycle. In mitosis, the cell is splitting in two to create two brand-new, identical daughter cells.  There are several stages that make up mitosis.

1. Prophase – the cell PREPARES to divide. The chromatin DNA condenses into “X”-shaped chromosomes. The spindle of the centrioles begins to form.2. Metaphase – Chromosomes line up in the MIDDLE of the cell cytoplasm. The spindle of the centrioles attaches to the centromere of the chromosomes.3. Anaphase – The chromosomes pull APART, with each sister chromatid pulling to either side of the cell.4. Telophase – With the chromosomes now located on the far opposite side of the cell, the nuclear membrane begins to reform around them, forming TWO new cells.  The spindle fibers of the centrioles disappear and the cell membrane begins to pinch together to become two separate cells.

C. Cytokinesis – This stage of the cell cycle occurs after mitosis ends.  In this phase, the cell membrane cleaves in half and two new daughter cells are formed.  These daughter cells are identical to the parent cell.  In plant cells, a new section of cell wall called the Cell Plate is built to separate the two new daughter cells.