If you can't read please download the document
Upload
ashley-stevens
View
226
Download
0
Embed Size (px)
DESCRIPTION
Figure 5.11
Citation preview
Cell Signaling to Transcription and Translation
Biology 160 We started by trying to understand this: Figure 5.11
The Role of Membranes in Cell Signaling
Watch Neutrophil explanation: Watch XVIVO animation: Want the
longer version? Check out: Click on Inner Life: Animation Intro to
the Immune System
Switch to Microbe Detectives presentation cause B cells and T cells
to grow and divide?
So how do microbes cause B cells and T cells to grow and divide?
Each cell has a receptor on its cell surface that recognizes a
specific part of a microbe. That receptor triggers a Signal
transduction pathway. This triggers gene expression (transcription)
that leads to protein synthesis (translation) that allows the cell
to grow (duplicate all its proteins that help to duplicate all its
organelles) and divide (mitosis). OK, so lets go into the nucleus
and remind ourselves about DNA structure Watch cell signaling video
DNA Structure DNA vs RNA Structure The four nucleotides found in
DNA
Differ in their nitrogenous bases. Are thymine (T), cytosine (C),
adenine (A), and guanine (G). RNA has uracil (U) in place of
thymine. The model of DNA is like a rope ladder twisted into a
spiral. Detailed representations of DNA
Notice that the bases pair in a complementary fashion. The Flow of
Genetic Information from DNA to RNA to Protein
DNA functions as the inherited directions for a cell or organism.
Copyright 2007 Pearson Education, Inc. publishing as Pearson
Benjamin Cummings How an Organisms Genotype Produces Its
Phenotype
An organisms genotype, its genetic makeup, is the sequence of
nucleotide bases in DNA. The phenotype is the organisms specific
traits (or what it looks like and how it functions), which arise
from the actions of a wide variety of proteins. Copyright 2007
Pearson Education, Inc. publishing as Pearson Benjamin Cummings The
one geneone polypeptide hypothesis states that the function of an
individual gene is to dictate the production of a specific
polypeptide. From Nucleotides to Amino Acids: An Overview
Genetic information in DNA is transcribed into RNA and then
translatedinto polypeptides. Transcription: From DNA to RNA
In transcription, Genetic information is transferred from DNA to
RNA. An RNA molecule is transcribed from a DNA template.
Transcription of an entire gene Initiation of Transcription
The start transcribing signal is a nucleotide sequence called a
promoter. The first phase of transcription is initiation: RNA
polymerase attaches to the promoter. RNA synthesis begins. RNA
Elongation The second phase of transcription is elongation:
The RNA grows longer. Termination of Transcription
The third phase of transcription is termination: RNA polymerase
reaches a sequence of DNA bases called a terminator. The Processing
of Eukaryotic RNA
The eukaryotic cell processes the RNA after transcription. RNA
processing includes: Adding a cap and tail Removing introns
Splicing exons together Translation: The Players
Is the conversion from the nucleic acid language to the protein
language. The Players mRNA tRNA Ribosome Messenger RNA (mRNA) What
are the rules for translating the RNA message into a polypeptide?
Triplets of bases Specify all the amino acids. Are called codons.
The Genetic Code The genetic code is shared by all organisms.
A firefly gene expressed in a plant!!! An mRNA molecule also has a
cap and tail that help it bind to the ribosome. Transfer RNA (tRNA)
tRNA Acts as a molecular interpreter.
Carries amino acids. Matches amino acids with codons in mRNA using
anticodons. Ribosomes Ribosomes Are organelles that actually make
polypeptides.
Are made up of two protein subunits. Contain ribosomal RNA (rRNA).
A fully assembled ribosome holds tRNA and mRNA for use in
translation.
Translation: The Process
Translation is divided into three phases: Initiation Elongation
Termination Initiation The first phase brings together: The
mRNA
The first amino acid with its attached tRNA The two subunits of the
ribosome Elongation Step 1, codon recognition
The anticodon of an incoming tRNA pairs with the mRNA codon.
Elongation Step 2, peptide bond formation
The ribosome catalyzes bond formation between amino acids.
Elongation Step 3, translocation
A tRNA leaves the P site of the ribosome. The ribosome moves down
the mRNA. Termination Elongation continues until the ribosome
reaches a stop codon. Review: DNA RNA Protein
The flow of genetic information in a cell cause B cells and T cells
to grow and divide?
So how do microbes cause B cells and T cells to grow and divide?
Each cell has a receptor on its cell surface that recognizes a
specific part of a microbe. That receptor triggers a Signal
transduction pathway. This triggers gene expression (transcription)
that leads to protein synthesis (translation) that allows the cell
to grow (duplicate all its proteins that help to duplicate all its
organelles) and divide (mitosis). On to the Cell cycle!