Lesson 1 - Introduction Flashcards
basic structural and functional units of life
cells
“all organisms are composed of one or more cells.”
“the cell is the structural unit of life”
- Matthias Schleiden
- Theodor Schwann
(1838-1839)
“cells can arise only by division from a preexisting cell”
Rudolf Virchow (1855)
Living things, though infinitely varied when viewed from the outside, are fundamentally __ inside
similar
transfer of characters or traits from the parents to their off springs
Heredity
differences between the characters or traits among the individuals of the same species
Variation
What do cells carry that define each species
hereditary information (DNA)
long, unbranched, double-stranded molecule formed by four types of nucleotides
DNA
forms DNA
nucleotides
Four types of nucleotides in the DNA
- Adenine
- Guanine
- Cytosine
- Thymine
charge of the DNA
negative
forms the nucleotide
- phosphate
- sugar
- base
link the nucleotides in each strand
covalent bonds
hold the two DNA strands together
hydrogen bonds
bond between the phosphate and sugar
phosphodiester bond
bond between the sugar and base
glycosidic bond
determines the genetic information
sequence of bases
two types of bases
- purine
- pyrimidine
purines
Adenine
Guanine
pyrimidine
Cytosine
Thymine
Uracil
hydrogen bonds between adenine and thymine
2
hydrogen bonds between cytosine and guanine
3
the first experiment which suggested that bacteria can transfer genetic information through a process called transformation
Griffith’s transformation experiment
full name of Griffith
Frederick Griffith (1928)
what type of bacteria did Griffith use
Diplococcus pneumoniae (Pneumococcus)
Smooth type (S)
- thick polysaccharide capsule
- smooth mucoid colonies
- pathogenic/virulent
Rough type (R)
- no capsule
- rough colonies
- non-pathogenic/avirulent
Who are the other scientists who had an experiment related to Griffith’s transformation experiment
- M.H. Dawson (1930) and
- J.L. Alloway (1932)
what did M.H. Dawson (1930) and J.L. Alloway (1932) do
- in vitro transformation
- mouse was not necessary
- extract from heat-killed S cells + live R cells -> live S cells
- purified biochemicals (proteins, DNA, RNA) from the heat killed S cells to see which ones could transform live R. cells into S cells
- discovered that DNA alone from S bacteria caused the bacteria to become transformed
Avery, MacLeod, McCarty
General Properties of Transforming Substance
- viscous, silky sheen
- loses activity in distilled water
- activity retained for months in physiological salt solution
- withstands heating at 65C for 30-60 minutes
- loses activity with increased acid concentration
showed that phages only injected their DNA into host bacteria, and that the DNA served as the replicating genetic element of phages
Hershey-Chase Experiment
what phages were used in the Hershey-Chase Experiment
T2 phages
the four scientists who codiscovered the double-helix structure of DNA, which formed the basis for modern biotechnolog
- Francis Crick
- Rosalind Franklin
- James Watson
- Maurice Wilkins
“DNA is made of nucleotides”
Phoebus Levene
“1 purine : 1 pyrimidine”
- Erwin Chargaff
- Rollin Hotchkiss
- Ronald Fisher
suggested that DNA is triple-stranded
Linus Pauling
provided X-ray diffraction photograph of crystalline DNA
- Rosalind Franklin
- Maurice Wilkins
All cells replicate their DNA by __ __
templated polymerization
the nucleotide sequence in one strand is __ to the other strand
complementary
- It is the segment of double stranded DNA.
- Runs from 5’ to 3’.
- has base sequence same as that of mRNA.
- also known as coding strand.
Sense strand
- aka template strand.
- runs from 3’ to 5’.
- complimentary to sense strand.
- in which transcription occurs.
Antisense strand
how many origin of replication in prokaryote
1
how many origin of replication in eukaryote
multiple
DNA fragment corresponding to one protein or RNA
Gene
dictates the nature of proteins, when and where they are to be made
genome
gene expression is a __ process
regulated
specify the transcripts and protein products
coding segments
serve as punctuations and regulatory sequences that contrl the local rate of transcription
non-coding regions
Long non-coding RNA length
~1000 - 10000 nt long with little to no protein-coding potential
are RNA molecules larger than 200 nucleotides
Long noncoding RNAs (lncRNAs)
LncRNA functions
- transcriptional activation
- transcriptional repression
- enchancer RNA
- scaffolding protein for chromatin remodeling complexes
- regulation of RNA splicing
- sequestration of miRNA
small, highly conserved non-coding RNA molecules involved in the regulation of gene expression
MicroRNAs (miRNA)
All cells transcribe portion of their __ into __
DNA to RNA
form of templated polymerization that faithfully rewrites DNA to RNA
transcription
serves as the template to produce RNA transcripts
noncoding strand
transcripts function as __ in the transfer of genetic information
intermediates
guides the synthesis of proteins
messenger RNA (mRNA)
process from DNA to protein
- replication
- transcription
- protein
single stranded polynucleotide closely related to DNA
RNA
bases of RNA
- adenine
- guanine
- cytosine
- uracil
RNA molecules is __ and can fold up into specific shapes
flexible
what does the shape of RNA enable
- recognize and selectively bind molecules
- catalyze some chemical changes
long, unbranched polymers of amino acids and are the main molecules that put the cell’s genetic information into action
proteins
what does the amino acid sequence determine
function of protein product
how many types of amino acids are there
20 amino acids
gives the protein a distinct chemical property
side chain
Three binding sites for tRNA
- aminoacyl site (A site)
- peptidyl site (P site)
- exit site (E site)
all cells use proteins as __
catalysts
all cells acquire and utilize __
energy
Different ways living organisms obtain their free energy
- organotrophic
- phototrophic
- lithotrophic
feed on other living things or the organic chemicals they produce
organotrophic
harvest sunlight and convert it into chemical forms that can be used by the cells
phototrophic
capture their energy from energy-rich systems of inorganic chemicals in the environment
lithotrophic
- encloses all cells
- which nutrients and waste materials must pass
plasma membrane
plasma membrane acts as a __ __
selective barrier
determine which molecules enter the cell
membrane transport proteins
those that are both hydrophilic as well as hydrophobic
Amphipathic molecules / amphiphilic molecules
cells produce molecules whose chemical properties cause them to __ into the structures that a cell needs
self-assemble
covers cells and interact with substances in the environment in highly specific ways
receptors
how can cells respond to specific stimuli
- altering their metabolic activities
- move from one place to another
- activating death pathways
cells are __, under constant regulation
robust
what do cells use to regulate cellular responses to maintain homeostasis
feedback circuits
Universal Properties of Cells (1-3)
- DNA is the genetic information of all cells
- DNA is synthesized via templated phosphorylation
- Gene is a DNA segment corresponding to one protein or RNA
Universal Properties of Cells (4-6)
- All cells transcribe portions of their DNA into RNA
- All cells translate RNA into proteins in the same way
- All cells use proteins as catalysts
Universal Properties of Cells (7-10)
- All cells acquire and utilize free energy
- All cells function as biochemical factories dealing with the same basic molecular building blocks
- All cells are enclosed in a plasma membrane
- All cells respond to stimulus and self-regulate
new genes are generated from __ __
preexisting genes
randomly modifies the DNA sequence through various types of error during DNA replication
intragenic mutation
creates a pair of identical genes within a single cell, which may then diverge in the course of evolution
gene duplication
occurs when two or more existing genes break and rejoin to make a hybrid gene
DNA segment shuffling
Different models for DNA replication
- Conservative model
- Semi-conservative model
- Dispersive model
Proved the semi-conservative model of DNA
Meselson-Stahl Experiment