IB Biology Unit 1

Unit 1: Cell iology

Cell Theory:

Cell Theory:

1. All living things are made up of cells

2. cells are the smallest units of life

3. cells come from preexisting cells

Exceptions to cell theory and why

1. Aseptate Fungal Hyphae: continuous cytoplasm, does not have septa

2. Muscle Fibres: multinucleated and have 1 continuous plasma membrane

3. giant algae: large unicellular organism

How do you calculate magnification

M = I/A

Define emergent Properties

Arise from the interaction of individual components in a complex system

Define cell differentiation

Newly formed cells have the ability to differentiate and become specialized. They all have an identical genome and the expression of certain genes makes them differenciate.

Gene Packing of active genes:

packaged in euchromatin for transcription

Gene packaging of inactive genes

packaged in heterochromatin

What are stem cells?

Unspecialized cells

key qualities of stem cells

Self renewal —> they can continuously divide/replicate

Potency —> differentiate into any specialized cell

what are totipotent stem cells?

Found in the embryo and can specialize into anything (T = furthest in the alphabet so the cells can specialize further into anything)

what are pluripotent stem cells?

Found in the embryo, can specialize into nearly anything and are research useful (pluri = multiple)

Applications for pluripotent stem cells:

Parkinson’s disease: nerve cells

what are multipotent stem cells?

derived from adult stem cells limited range of differentiation (Multi —> more —> more years old)

Applications for multipotent stem cells

Can be used to treat leukaemia: Bone marrow can specialize into any type of blood cell

What are unipotent stem cells?

adult stem cells, can only divide into the same type of cell (uni = 1)

Applications for unipotent stem cells:

Used to treat burn victims: skin cells can make more skin cells

Stargard’s Disease

Genetic, progressive blindness: embryonic stem cells are applied to retinal cells

Artificial stem cell techniques: somatic cell nuclear transfer

creation of embryonic clones by fusing a diploid nucleus w/ an enucleated egg

Artificial stem cell techniques: Nuclear reprogramming

Induce a change in gene expression of a cell so it can differentiate into a desired cell

Light microscopes

they can view living things

they have a lower magnification

Electric Microscopes

High magnification

they can only view dead specimens

Draw and label a prokaryotic cell

Pili

70 S ribosomes

Nucleoid

Plasmid

Slime capsule

Cell wall

Cell membrane

Functions of components of a prokaryotic cell:

Pili

70 S ribosomes

Nucleoid

Plasmid

Slime capsule

Cell wall

Cell membrane

Pili: helps with adhesion

70 S ribosomes: sites for protein synthesis

Nucleoid: contains a singular strand of DNA

Plasmid: small independent DNA

Slime capsule: Made of polysaccharides

cell wall: maintains shape

cell membrane: controls what enters and leaves the cell

flagellum: works as a motor

how do prokaryotic cells divide?

Binary fission:

1. A circular strand of DNA is copied in the cell

2. 2 DNA loops attach to membrane

3. membrane elongates and pinches off through cytokinesis

What is the difference between a eukaryotic cell and a prokaryotic cell?

Eukaryotic cells:

compartmentalized

mitochondria

chloroplasts

double membrane

nucleus

Parts of a eukaryotic animal cell and their functions

cell wall: maintains shape

cytoplasm: medium for chemical reactions

80 S ribosomes: protein synthesis

ER: membrane network

• RER: protein synthesis

• SER: creation/storage of lipids

Golgi body: storage/processing proteins

mitochondria: energy

nucleus: DNA storage

Lysosome: sac w/ enyzmes

Parts of a eukaryotic animal cell and their functions

cell wall: maintains shape

80 S ribosomes: protein synthesis

ER: membrane network

• RER: protein synthesis

• SER: creation/storage of lipids

Golgi body: storage/processing proteins

mitochondria: energy

nucleus: DNA storage

vacuole: hydrostatic pressure

chloroplasts: site of photosynthesis

cell wall: external covering

cytoskeleton: boning/structure

draw and label a eukaryotic animal and plant cell

Fluid Mosaic Model:

Functions of phospholipids:

Amphipathic

polar head: hydrophilic

non-polar tail: hydrophobic

Function of Channel Proteins

transmembrane protein:

• passive transport of ions at a fast rate

Function of glycoproteins

transmembrane protein:

• alter their shape to translocate solute, active transport

(G for glyco: G for gemini —> change)

Functions of integral proteins

Transmembrane protein:

• keep toxins out

Functions of peripheral proteins

temporarily attached:

• lies on the surface of the membrane

• cellular communication and binding site for carbohydrate

carbohydrate:

Binding point and identifies the cell

cholesterol:

stabilizes the membrane, amphipathic, reduces the fluidity of the membrane and prevents crystallization.

Davson Danielli

phospholipids sandwiched between a layer of proteins on each side

Membrane transport: Passive transport

goes along the concentration gradient and is divided into: facilitated diffusion, osmosis and simple diffusion

Facilitated diffusion:

Through channel proteins, large/polar molecules move

simple diffusion:

movement of small particles from high concentration to low

osmosis:

net diffusion of H2O —> from low solute concentration to high

active transport is divided into:

direct and indirect

what is indirect:

indirectly uses energy: coupling molecules —> a molecules using another molecules ATP (Piggy backing)

what is direct:

a molecule using its on ATP

what factors affect diffusion?

temperature, molecule size, gradient steepness

what is vesicular transport

Substances are transported within a cell in membrane-bound vesicles.

Hypertonic

too much solute outside so water escapes the cell and makes it shrivel

hypotonic

there is too much solute in the cell so water enters and makes it bulge

isotonic

balanced osmolarity

sodium potassium pump:

active transport: 3 sodiums leave the cell while 2 potassiums enter through the SP pump

Endosymbiotic theory

1 prokaryotic cell engulfed another and engulfed mitochondria and chloroplasts

evidence for endosymbiosis

MAD DR

Membrane: double membrane

Antibiotic resistance: bacterial origin

Division: similar to binary fission

DNA: naked and circular

Ribosomes: 70 S ribosomes in chloroplasts and mitochondria

eukaryotic cell division

Cell cycle:

interphase

• making DNA

• Cellular functions

G1: cel is growing and producing more cytoplasm

S: Synthesis, DNA is replicated

G2: cell prepares for division

Mitosis

Cytokinesis

Steps of mitosis

PMAT

Prophase: chromosomes supercoil, microtubules grow on opposite sides

Metaphase: Spindle fibres grow, attach to the centromere, and chromosomes align in the middle

Anaphase: spindle fibers pull sister chromatids apart

Telophase: spindle fibers are dissolved and nuclear membranes form around each cell

cytokenisis: microtubule breaks the cell in 2

What are the cell checkpoints:

G0: resting state after cell divides

G1: checks nutrients, growth factors and DNA for damage

G2: check size and error in DNA replication

Mitotic index calculation

cells in mitosis/ number of cells

Necrosis

Murder: an injured cell, lacks nutrients, has toxins

• cell swells —> increases in osmotic pressure

• cell bursts —> can cause damage in surrounding cell

Apoptosis

Cell suicide: necessary death because of mutations

• cell contents are repackaged

• cell shrinks + breaks down into apoptotic bundles

• apoptotic bodies are engulfed

Cancer: what are metasis

cells from primary to secondary structure

1. tumour can invade other tissue

2. can travel into blood supply

3. invade healthy cells and start dividing

How does smoking increase chances of cancer?

strong positive correlation between both:

• 4000 chemicals —> 600 are carcinogenic

normal cell vs cancer cell

normal cell:

• small cytoplasm

• regulated division

• clear structure

Cancer cell:

• large cytoplasm

• irregular/rapid division

• unclear structure

mutagens: what are they?

Mutated genes: changes in the genetic sequence

What causes mutagens:

exposure to ultraviolet waves

x rays

viruses like hepatitis

what are oncogenes?

genes with potential to cause cancer

Pro-oncogenes, what are they?

stimulate growth/cell cycle, can make it very rapid and irregular

tumor repressor genes:

repress the cell cycle, apoptosis

what happens if tumor repressor genes stop working?

higher risk for cancer