Topic 1: Cell Biology

explain the three principles of cell theory

explain the three principles of cell theory

cells are the smallest units of life, all living organisms are composed of cells, and all cells come from pre-existing cells

skeletal muscle

an exception to the cell theory; made up of muscle fibers, enclosed inside a membrane, much larger than most cells

giant algae

an exception to the cell theory; only contains a single nuclei therefore not multicellular; ex. Acetabularia

asepate fungi

an exception to the cell theory; consists of thread-like structures that are not divided containing a single nucleus, instead there a divisions of undivided hypha that contain many nuclei

unicellular organisms

organisms consisting of only one cell

list the functions of life

1. nutrition

2. growth

3. response

4. excretion

5. metabolism

6. homeostasis

7. reproduction

compare Paramecium and Chlamydomonas in carrying out the functions of life

Nutrition: P feeds through endocytosis while C photosynthesizes

Growth: P increases by accumulating organic matter while C increases through photosynthesis

Response: P reacts to touching solid objects while C senses light brightness

Excretion: P expels CO2 while C expels O2

Metabolism: both produce enzymes to carry out different reactions

Homeostasis: both keep internal conditions within limits

Reproduction: both reproduce asexually using mitosis or meiosis

multicellular organisms

organisms consisting of multiple cells

SA:Vol

as as cell grows larger, SA:Vol become smaller

explain why SA:Vol is important to maintain at a greater ratio

the rate at which materials enter or leave a cell depends on SA, the rate at which materials are produced depends on the volume; maximizing the ratio allows optimum cell activity

explain how organisms maximize SA:Vol

1. cells divide

2. cells compartmentalize: use membranes to carry out metabolic processes (organelles)

   1. organelles: made up of membranes to maximize space for reactions

3. some organs fold up

4. some have very thin membranes

differentiation

when a cell uses only the gene from its genome that is needed to carry out a specific function; results in specialized cells (ex. lungs, cardiac, blood, etc.)

genome

an organism’s entire set of genes; each cell has the full genome so it can carry out and kind of function

emergent properties

arise from the interaction of component parts of a complex structure; the whole organism can achieve more than the individual cells that make them up

stem cells

cells that have the capacity to divide and to differentiate along different pathways to perform different functions; human embryos consist of solely stem cells in their early stages but then commit themselves to a pattern of differentiation; found in bone marrow, skin, and liver

list the different categories of stem cells

1. totipotent: can become any cell type

2. pluripotent: can become any type except embryonic membrane

3. multipotent: can become a number of different cell types

ethics

moral principles that allow us to decide whether something is morally right or wrong; ethics play a huge role in the discussion of using stem cells for therapeutic use

give an example of therapeutic stem cell use

leukemia treatment: leukemia is a type of cancer that causes an abnormally large number of white blood cells produced in the bone marrow

• stem cells are taken from a large bone, typically the pelvis, and stored

• intense chemotherapy is done to kill the cancer cells in the bone marrow

• stem cells are returned and produce healthy blood cells

• usually ends up curing the patient

magnification calculation

magnification = size of image/size of specimen

ex. magnification = 10µm/20µm = 10,000µm/20µm = 500

size of specimen calculation

size of specimen = size of image/magnification

ex. size of specimen = 48µm/x4000 = 48,000µm/x4000 = 12µm

resolution

the ability of the microscope to show two close objects separately in the image; depends on the wavelengths of the rays being used to show the image; short wavelengths provide better resolution

transmission electron microscopes (TEM)

used to view ultra-thin sections

scanning electron microscopes (SEM)

produce an image of the surfaces of structures

prokaryotic cells

came before eukaryotes; no nucleus; simple cell structure generally without membrane bound components

draw and label a prokaryotic cell

(see image)

binary fission

the process in which prokaryotic cells divide

outline the process of binary fission

1. duplication of chromosomes and separation of copies

2. continued elongation of the cell and movement of copies

3. cleavage forms

4. division into two daughter cells

eukaryotic cells

came after prokaryotes; contain a nucleus; have membrane bound organelles

draw and label a eukaryotic cell

(see image)

explain the fluid mosaic model of membrane structure

1. phospholipid bilayer: composed of a hydrophilic phosphate head and two hydrophobic fatty acid tails (amphipathic)

2. integral proteins: proteins embedded into the phospholipid bilayer

3. peripheral proteins: proteins attached to an outer surface

4. glycoproteins: have sugar units attached on the outer surface of membrane

5. cholesterol: component of animal cell membranes, affects fluidity at different temperatures

list examples of membrane proteins

1. hormone receptor - integral

2. cadherin for cell-to-cell adhesion integral

3. cytochrome c - electron transport

4. calcium pump - active transport

diffusion

the passive movement of particles from a region of high concentration to a region of low concentration

simple diffusion

some molecules make it through the partially permeable membrane between the phospholipid molecules

facilitated diffusion

some molecules make it through the partially permeable membrane but are unable to make it through solely the phospholipids, channel proteins are needed

osmosis

the passive movement of water across the membrane; water is a solvent so it follows the solute

hypertonic

the surrounding solution has a higher concentration/osmolarity

hypotonic

the surrounding solution has a lower concentration/osmolarity

isotonic saline

a solution of salts, used for some procedures

active transport

the movement of substances across the membrane using energy from ATP; they work in one direction only

antiporter

a membrane protein that transports substances in both directions

Na+/K+ -ATPase

an ATPase, helps to transmit nerve impulses in axons

endocytosis

takes substances in; endo = inner, within

exocytosis

transports vesicles from one cell to another; exo = outer

endosymbiotic theory

proposes that eukaryotic cells evolved from symbiotic relationships between different prokaryotic cells; suggests that organelles like mitochondria and chloroplasts were once free-living bacteria that were engulfed by a host cell and formed a mutually beneficial relationship

explain what happens to the DNA during mitosis

condensation: the chromosomes become shorter and fatter

supercoiling: coiling… the process of which condensation occurs

sister chromatids

the two components of the chromosome that are held together at the centromere

outline the phases of mitosis

IPMATC! Interphase Prophase Metaphase Anaphase Telophase Cytokinesis (see image)

cytokinesis

the division of the cytoplasm

mitotic index

ratio between number of cells in mitosis in a tissue and the total number of observed cells

mitotic index = number of cells in mitosis/total number of cells

cell cycle

the sequence of events between cell division

interphase

active phase of the cell’s where functions are carried out; consists of the G1 phase, S phase, and G2 phase

cell division

division of the cell…

oncogenesis

the formation of tumors

oncogenes

genes in charge of the cell cycle