IB BIO: Cells (1)

Cell

Cell

Smallest unit of life

Cell theory

1. All living things are made of cells

2. Cells are the smallest units of life

3. Cells can only be formed by division of pre-existing cells

Multicellular organisms have [...] to carry out various functions

Specialized cells (organelles)

Unicellular organisms carry out [...] in that cell

all functions of life

Organelles carry out various [...] functions in the cell

Metabolic (converting food to energy)

Cells multiply by three types of division:

Mitosis, meiosis, binary fission (only prokaryotes)

All cells descend from [...] ancestors

Simpler common

First cells must have arise from [...]

Non-living material (organic carbon containing compounds)

Origin of eukaryotic cells can be explained by [...]

Endosymbiotic theory

All living organisms carry out the [...]

Functions of life

Life functions

1. Nutrition

2. Growth

3. Reproduction

4. Response to stimulus

5. Excretion

6. Homeostasis

Multicellular organisms have...

Specialized cells to carry out specific functions (organelles)

Viruses are classified as living (T/F)

False; they are not classified as "living"

Viruses do [...] carry out all the [...] functions independently

not, life

Because viruses cannot carry out all of the life functions independently, they must [...] a [...] to survive

invade, host cell

Evidence for cell theory:

1. Robert Hooke coining the term "cell" after looking at cork sections under a microscope

2. Antonie van Leewenhoek discovering cells

3. Pasteur's experiment

4. Robert Remak discovering cell division under a microscope

Scientific Process

observation -> question -> hypothesis -> test -> refute/corroborate -> theory

Pasteur's experiment

Disproved the idea of spontaneous generation through the use of swan necks. Open exposure to air would cause bacteria to occur in a broth, while stopping entry of airborne particles (through swan necks) would prevent growth from occurring entirely

The [...] of a cell is the [...] for materials between the inside and outside of the cell

plasma membrane, surface of exchange

As a cell becomes [...], it requires [...] to be imported and produces more products and wastes to be exported

larger, more resources

Larger cell [...] requires more [...] across the membrane

volume, exchange

As the cell gets larger, the [...] to [...] ratio becomes [...]

surface area, volume, smaller

The [...] become less efficient with [...] cell size

exchange processes, increasing

Diffusion pathways are shorter and more [...] in [...] cells with a larger surface area to volume ratio

more efficient, smaller

Why are cells small?

To maintain a high surface area to volume ratio

Plasma membrane

Selectively-permeable phospholipid bilayer

[...] occur inside the plasma membrane

metabolic reactions, (turning food into energy)

A larger SA:Vol ratio means [...] cells can act more [...] moving nutrients into the cell and wastes out of the cell

small, efficient

There is more unit of [...] for every unit of [...] with a larger SA:Vol ratio

membran, volume

WIth a large SA:Vol ratio, diffusion pathways are [...], and therefore more [...]

shorter, efficient

With shorter diffusion pathways, molecules do not have to travel so far, so it takes less [...] and [...]

time, energy

[...] are easier to generate which makes diffusion less difficult

concentration gradients

A large SA:Vol ratio is not an advantage to [...] because they lose [...] very quickly

small warm-blooded mammals, heat

To maximize SA:Vol ratio, cells [...]

divide

Cell differentiation

Cell becomes specialized for a specific structure or function

In eukaryotes, cells use membranes to carry out metabolic processes called [...]

organelles

The intestine [...] to maximize the SA:Vol ratio making absorption of food molecules more [...]

folds up, efficient

Alveoli in the lungs maximize the surface area for [...]

gas exchange

Emergent properties

The idea that the whole organisms can achieve more than the individual cells that make them up;{organelles -> cells ->tissues -> organs -> organ systems -> organisms}

Emergent properties are caused by [...] allowing them to perform tasks

organelle interaction

Specialized tissues can develop by [...] in multicellular organisms

cell differentiation; {examples: lung, neuron, blood cells...}

Differentiation depends on the [...] of some genes and not others in a cells genome

expression; (means activation)

Cell differentiation expression is triggered by [...]

environmental change

Stem cell

An unspecialized cell that can develop into a specialized cell

Stem cells ability to [...] and [...] is necessary in embryonic development, allowing them to be usable for therapeutic uses

divide, differentiate

Stem cells divergent pathways

Totipotent, pluripotent, multipotent,

Totipotent

Can become any cell type

Pluripotent

Can become any type except embryonic membrane

Multipotent

Can become a number of different cell types

Once a stem cell has [...], it can only make more stem cells or the [...] cell type

differentiated, differentiated

All cells in the body carry the [...] genes in their nuclei

same

What makes a cell different is which genes are [...]

expressed

Advantage of electron microscopes?

Deliver high resolution, 3D surface images of structures

What do transmission electron microscopes vs normal light microscopes?

Give a view inside cells and organelles

[...]mm = [...]um

1mm = 1000um

Magnification formula

measured length/scale bar length

Actual size formula

measured length/magnification

Eukaryotes have a much more [...] structure than prokaryotes

complex

Prokaryotes are [...] than eukaryotes and came [...] in terms

smaller, first

Prokaryotic cell parts

Cell wall, plasma membrane, pili, cytoplasm, nucleoid, ribosomes, flagella

Cell wall

Protects and supports the cell structure

Pili

Attach to other bacteria for DNA transfer

Nucleoid

Closed-loop of bacterial DNA in a condensed area (does not have a nuclear membrane)

Flagella

whiplash-like motion causes movement

Cytoplasm

Contains enzymes for metabolism

Prokaryotes generally do not have [...] components

membrane bound

Prokaryote protein synthesis

70S ribosomes (unique to prokaryotes)

Prokaryotes reproduce by [...]

binary fission

Binary fission

Asexual reproduction where chromosomes duplicate and the cell elongates until division

Population growth by binary fission is [...]

exponential

Binary fission stops when the population reaches [...]

Carrying capacity; (population increases until there are no more resources to support growth))

Eukaryotes have [...]

Membrane bound organelles

Eukaryotes are [...] than prokaryotes and came [...]

larger, after

Endosymbiotic theory

Small unicellular organisms were engulfed that would become apart of larger organisms and eventually specializing to become organelles within the cells

Symbiotic relationship

Larger cell provides a habitat for smaller prokaryote and in return is rewarded by the products of the prokaryote (proteins, ATP)

Ideas supporting the endosymbiotic theory

1)Cell organelles are of comparable size to prokaryotes, 2) Some organelles have their own DNA 3) Evidence provided by the fossil record

Mitochondria

Site for cellular respiration: converting glucose into ATP

Free ribosomes

Produce proteins

Nucleus

Membrane-bound organelle that contains all genetic information

Rough endoplasmic reticulum

Ribosomes on rough ER produce proteins to be exported from the cell

Lysosomes

Organelle containing digestive enzymes to break down dead cell parts for recycling

Golgi apparatus

Modifies and "packages" proteins produced in the rough ER to be exported by the cell via exocytosis

Smooth endoplasmic reticulum

Synthesizes lipids and carbohydrates

Organelles animal cell specific include:

centrioles (used in cell division), and lysosome

Organelles plant cell specific include:

Cell wall, chloroplasts, and vacuoles (in most cases)

Chloroplast

Site for photosynthesis and contain chlorophyll

Vacuole

Stores water, sugars, and wastes

Electron microscopes have a higher resolution than light microscopes because they use a beam of [...] instead of light waves

Electrons

TEM

Transmission electron microscope

Nucleus pores

Allows molecules (RNA & ribosomes) to pass through

Nucleus shape is maintained by the [...]

Nuclear lamina (protein net lining the inside of the nucleus)

Plasma membrane functions

1. Hold the cell together

2. Controls imports/exports (diffusion, osmosis, active transport)

3. Protection

4. Cell signaling & immunity

5. Bind to other cells & molecules

6. Site for biochemical reactions (enzymes)

Phospholipid bilayer consists of

Hydrophilic phosphate head and a hydrophobic hydrocarbon tail

Hydrophobic

Repelled by water

Hydrophilic

Attracted to water

Cholesterol

Affects membrane fluidity at different temperatures

Amphipathic

Having hydrophilic and hydrophobic properties

Phospholipids form bilayers in water due to the [...] of phospholipid molecules.

Amphipathic properties

Phosphate heads bind to the hydrogen in water because of their [...]

Negative charge (hydrophilic)

Hydrocarbon tails have no charge so will [...] with water

Not bind (hydrophobic)