Unit 1: Intro to Cells

basically just review of cells and organelles

cell

small, membrane enclosed unit

• filled w/ aqueous solution

• building block of life

• vary in size & shape

• all come from a single ancestor

central dogma

DNA → RNA → protein

dna synthesis (replication), transcription, translation

DNA

• store genetic info

• made of nucleotides (A, T, C, G)

• codons interpret genetic code

• filler DNA does not code for RNA, but it can have other functions

mutation

change in the DNA sequence of an organism

• beneficial, harmful, or neutral

genome

entire library of genetic info in its DNA

• ___ size varies across organisms

• comparing ___ sequences reveals heritage

• instructions for cell formation, function, & behavior

• each cell contains a complete copy of the ___, but different cells express different genes

  • gene expression is affected by internal & external signals

cell theory

1. All organisms consist of one or more cells

2. Cells are the basic unit of structure for all organisms

3. All cells arise only from preexisting cells
   
   Matthias Schleiden: botanist, studied plant cells
   Theodor Schwann: studied animal cells

cell membrane

phospholipid bilayer that surrounds the cell

• defines the boundary of the cell

cytoplasm

aqueous solution within cell membrane, contains things that arent membrane bound (both the liquid component & other stuff)

cytosol

just the liquid part of the inside of the cell

• site of chemical rxns such as glycolysis

prokaryotic

no nucleus or membrane bound organelles

• more simple

• varying shapes & sizes

• can live in a variety of environments

• can live in colonies

eubacteria

prokaryotes
true bacteria

live in “normal” environments (soil, water, humans)

archaea

prokaryotes
extremophiles

• like environments similar to early earth

• also found in the gut

• eukarya is more similar to ___ than bacteria

eukaryotic

DNA contained in nucleus

• contains membrane bound organelles (endoplasmic reticulum, golgi apparatus, lysosome, endosome, peroxisome, mitochondria, chloroplasts)

nucleus

where all the genetic info is stored in the cell

• chromosomes are condensed into X shape during cell division (coiled), making them unavailable for transcription

• only uncoiled DNA can be used for transcription

nuclear envelope

contains pores that allow molecules to enter & leave the nucleus

mitochondria

generate ATP from food to power the cell

• double membrane

• cristae: folds in the inner membrane of a mitochondria

• has its own DNA

chloroplast

capture energy from sunlight

• double membrane

  • more internal membrane

• has its own DNA

endoplasmic reticulum (ER)

assembles cell membrane components

• continuation of nuclear envelope

• next to nucleus

rough ER

contains many ribosomes

• proteins move from rough ER → golgi apparatus

ribosome

makes proteins (location of translation)

smooth ER

lacks ribosomes

• synthesizes lipids & phospholipids

golgi apparatus

modifies & sorts molecules (proteins) sent by the rough ER

• contains vesicles which deliver the proteins (like an uber) to their final location

lysosome

breaks down molecules

peroxisome

where hydrogen peroxide is isolated

cytoskeleton

responsible for directed cell movements

• constantly shifting, allowing for cell movement

• consists of three filaments: microfilaments (actin), intermediate filaments, and microtubules

microfilaments (actin)

muscle contraction & cell movement

• smallest size of the three filaments that make up the cytoskeleton

intermediate filaments

tensile strength

• middle size of the three filaments that make up the cytoskeleton

microtubules

mitosis spindles (pull apart chromosomes

direct vesicle transport

• largest size of the three filaments that make up the cytoskeleton

model organisms

easy to study

easy to propagate (breed)

results are widely applicable

E. coli

model organism

gram neg bacillus

• used to study DNA coding & cell replication

Saccharomyces

model organism
fungi genus, includes yeast

• used for cell division studies for mitosis

common water cress

model organism

• used to study plant mechanisms

Drosophila (fruit fly)

model organism

• used to study genetics

Nematodes

model organism

• used to study development & apoptosis

Zebra fish

model organism

• used to study development

• transparent for the first two weeks of life

mice

model organism

• manipulate their genes & mimic human diseases

human cell lines

population of human cells grown in a lab (in vitro) that can divide and replicate indefinitely, used for study

• most originated from cancer cells or embryonic cells

fibroblasts

make up connective tissue

myoblasts

develop into muscles

epithelial cells

skin cells

light microscope

• led to the discovery of cells

• Robert Hooke (1665) viewed “cork” cells

• Antoni van Leeuwanhoek (1674) viewed live cells in canal water

• fixed specimen, limited resolution

phase contrast microscope

light microscope enhanced w/ optics

• live specimen, limited resolution

• look at living tissue

• allows internal structures to be seen

fluorescence microscope

see molecules labeled w/ fluorescent dyes

• see ~20nm objects

• clear image; confocal scanning, 3D

electron microscope

fixed or dead images

transmission EM: scans thru specimen

scanning EM: scans surface

endosymbiont theory

mitochondria & chloroplasts most likely evolved from engulfed bacteria

• first event: host cell engulf bacteria ( → mitochondria)

• second event: host cell engulf photosynthetic bacteria ( → chloroplast)

• mutual codependency: engulfed bacteria gain shelter, host cell gains resources

• nitroplast: nitrogen fixing organelle

  • kind of went thru its own endosymbiotic theory

endocytosis

take in molecules thru the membrane

• eukaryotes only: prokaryotic membrane lacks the fluid to form vesicles

exocytosis

release molecules thru the membrane

• eukaryotes only: prokaryotic membrane lacks the fluid to form vesicles