GCD 3033 Principles of Cell Biology Exam 1

___ are the fundamental unit of life

cells

universal properties of cells

• possess a plasma membrane

• DNA is the store of hereditary information

• RNA is an intermediate in information transfer

• use ribosomal machinery for protein synthesis

• ATP is the energy currency

• carbon-based metabolism

transcription

process of copying using the same language

translation

process of converting from one language to another

why do all cells share some related DNA sequences?

because all present-day cells have evolved from common ancestor

cell discovery timeline

• 1660s - first description of cells by hooke and leeuwenhoek

• 1830s - cells are building blocks of plant and animal tissues

• 1860s - pastuer: living organisms do not arise spontaneously

• 1870s - 1st observations of cell division, chromosomes

what resolution can you see with your bare eyes?

200 micrometers

what resolution can you see with a light microscope?

0.200 micrometers

detection

ability to perceive the presence of an object

resolution

ability to discriminate between two objects that are close together, limited by the wavelength of light

contrast

to detect an object , it must contrast with its surrounding

methods used to enhance contrast (4)

1. bright field

2. phase / interference contrast

3. fluorescence microscopy

4. confocal fluorescence microscopy

bright field

is low contrast images in living cells, can sometimes be fixed and stain to add contrast

phase / interference contrast

look at structures that refract light (takes advantage of speed of light in cytosol)

fluorescence microscopy

stains specific structures with fluorescence dyes

confocal fluorescence microscopy

optical sectioning of thicker samples with laser beam

blue dye in stain cells usually indicate

negatively charged molecules (DNA, RNA)

red dye in stain cells usually indicate

positively charged molecules (proteins)

electron microscopy

• resolution is 0.2 nanometers

• is used to see smaller organelles

prokaryotic cells

• no nucleus

• most are single celled organisms

• contains cell wall

• smaller genome

• includes bacteria and anchaea

eukaryotic cells

• membrane bound nucleus

• single cell and multicellular organisms

• larger genome

• bigger and more elaborate

• includes animals, plants and fungi

nucleus

• largest organelle

• stores DNA

• surrounded by nuclear envelope (membrane)

• traffic in and out is regulated by nuclear pores

• site of DNA replication and transcription, RNA processing and ribsome assembly

mitochondria

• present in all eukaryotic cells

• double membrane structure

• contain its own DNA and reproduce by division

• DNA sequence is related to bacterial DNA sequences

• evolved from bacteria engulfed by ancestral cell

• performs cellular respiration

• powerhouse (generates ATP and oxygen)

chloroplasts

• present in plants and alga

• evolved from photosynthetic bacteria

• contains its own DNA and reproduces by division

• triple membrane structure

• third membrane contains chlorophyll (traps energy from sunlight)

• performs photosynthesis

Endoplasmic Reticulum (ER)

smooth

• does not have bound ribosomes: is the site of steroids horomone synthesis

rough

• has bound ribosomes and is the site of synthesis of transmembrane proteins

golgi apparatus

• stack of flatten membranes near nucleus

• receives and modifies molecules made in ER

• packages them for delivery to other locations

lysosomes

• small irregularly shaped

• site of intracellular digestion

• particularly abundant

• filled with undigested junk

peroxisomes

• small membrane enclosed organelles

• contained environment for the generation and degradation of toxic molecules

transport vesicles

• vesicles involved in transportation between different membrane compartments

• transports from plasma membrane inward is endocytosis

• transports to plasma membrane for secretion is called exocytosis

cytosol

• non-membrane containing cytoplasm

• concentrated mixture of molecules

cytoskeleton

contains three filament systems

• actin-based - used for contraction and transport

• intermediate filament based - used for mechanical stabilization

• microtubule based - used for support and transport

yeast (S. ceravisae)

advantages

• simple eukaryote

• carries out basic cellular functions

• good genetics

• used to study organization of chromosomes and cell division cycle

• some human genes can rescue mutation in yeast genes

disadvantages

• not multicellular

nematode worm (C. elegans)

advantages

• slightly smaller and simpler than drosophila

• detailed knowledge of cell fate from fertilized egg

• used for programmed cell death and animal development

disadvantages

• none

fruit fly (D.melanogaster)

advantages

• good medol for insect and animal development

• easy to grow in lab under controlled conditions

• numerous genetic mutations available

disadvantages

• none

zebra fish (danio rerio)

advantages

• easily maintained in fresh water

• transparent embryos

• useful for study of early development in live animal

mouse

advantages

• good model for mammalian development and disease

• genes closely related to human genes

• rapid generation time

humans

advantages

• human genome project and large number of genetic defects

• good organism for self reporting

• sequenced genome

disadvantages

• large genome size and generation time

structure of DNA

contains two complementary strands that run antiparallel

building blocks of DNA

phosphate + sugar (dexoyribose) + base

four different types of bases for DNA

1. purine

   1. adenine

   2. guanine

2. pyrimidine

   1. thymine

   2. cytosine

four different types of bases for RNA

1. purine

   1. adenine

   2. guanine

2. pyrimidine

   1. uracil

   2. cytosine

what shape does the two strands of DNA create?

double helix (10bp/turn)

different organisms have ___ DNA or nucleotide

different

how are nucleotide and amino acid sequences related?

The sequence of nucleotides in a gene specifies the amino acid sequence of a protein.

gene expression

is the process by which DNA nucleotide sequence of a gene is transcribed into an RNA nucleotide sequence and then translated into the amino acid sequence of a protein.

genome

is the complete set of information in an organisms DNA

chromatin

is the complex of DNA and protein

how many chromosomes are there in a human?

47 ( 22 homologous pairs and 2 sex determining chromosomes)

human karyotype

this is a display of all 46 chromosomes used to identify chromosomal abnormalities due to rearrangements or losses

how many origins or replication does a chromosome have?

multiple per chromosome