1. what is dna? 2. list anything you know about dna (from readings, class… · 2018-09-10 · list...

1. What is DNA?2. List anything you know about DNA

(from readings, class, TV…?)

Before we begin, let’s investigate the way DNA molecules are set up!

http://learn.genetics.utah.edu/content/molecules/builddna/

What is DNA?

DNA is the genetic material found in cells Stands for: “Deoxyribonucleic Acid” Is made up of repeating nucleic acids It’s the “Unit of Heredity”

DNA is found in the cytoplasm of prokaryotes and the nucleus of eukaryotes

The nucleus of a human cell contains 30,000 or more genes in the form of DNA called a genome

Purpose: DNA controls the production of proteins in the cell

▪ This is essential to life!

▪ DNA RNA Proteins

DNA is packaged tightly into pieces called chromosomes that are visible during cell division

Each chromosome includes several thousand genes

Each gene contains the directions to make one or more proteins

▪ Proteins are made of amino acids

These proteins play a key role in the way we look and grow…ever hear someone say “it’s in your genes?”

One Chromosome

Contains many genes

Each gene codes for a proteinEx. Keratin protein

Specialization▪ In embryo, all genes on the

DNA is “on”. This undifferentiated cell (stem cell) can develop into any type of cell.

▪ Specialization occurs when certain genes are turned “off” and other genes remain “on” – making a particular type of cell▪ Ex. Muscle cells and Nerve

cells in your body have the same DNA, but they have different genes activated.

DNA is comprised of two strands that twist around each other, called a double helix

▪ Discovered by Watson and Crick in 1953

“Twisted ladder structure”

Think of DNA as a spiral staircase!

DNA is a made of building blocks called nucleotides

A nucleotide is made of:▪ one phosphate

▪ one 5-carbon sugar (called deoxyribose)

▪ one nitrogen base▪ Adenine

▪ Thymine

▪ Guanine

▪ Cytosine

Nucleotides put together make up the DNA strand!

The sides, or “backbone” of the DNA are composed of alternating phosphate-sugar groups

Each “rung of the ladder” is made up of complementarynitrogenous base pairs

The four bases are A (adenine), T (thymine), G (guanine), and C (cytosine)

▪ A pairs with T (2 H Bonds)

▪ G pairs with C (3 H Bonds)

They form weak hydrogen bonds that hold the DNA strand together and are the reason DNA can be replicated

▪ A::T forms 2 H-bonds, and C:::G forms 3 H-Bonds

Phosphate-purple Sugar- blue Adenine-red Thymine-green Guanine-yellow Cytosine-orange

Go to: Socrative.com Click on: Student login Type room XX7CWRJG

Labe the diagram with the following terms: Nucleotide, Sugar, Phosphate, Base, Hydrogen Bonds

A B C

D

E

1. DNA is packaged into pieces. What are these pieces called?

2. There are thousands of genes on a chromosome. A single gene contains the directions to make what?

3. The base adenine (A) always pairs with ____________, while the base guanine (G) always pairs with _________________.

Locate your DNA paper model sheet. You will be completing this with your partners. When finished:

▪ Anaerobic graphing lab

▪ Post Assessments

▪ Extra Credit Assignment

Making a new strand

DNA replication is the process of producing 2 identical replicas from one original DNA molecule▪ Replicate means “to copy”

During replication, the DNA molecule separates into two strands, and builds two new complimentary strands using the base pairing rules (A::T, C:::G)

The molecule is unwound and “unzipped” with the help of helicase, an enzyme!

Step 1: DNA unwinds, then “unzips,” exposing the N-bases (remember, the bases are ATCG)

Step 2: New DNA N-bases are added to each side of the molecule, making two separate strands▪ If the unzipped side read ATCG,

then TAGC would be added to that side. Now it is an independent strand!

http://www.youtube.com/watch?v=hfZ8o9D1tus

Each new DNA strand (daughter chromosome) is made up of 1 strand from the original DNA (blue) and one new strand (red)

Given one strand, you can always find the other strand using base pairing rules!

Let’s practice! If the DNA sequence of bases on one strand was

G C T A C A T, what would the complementary side be during replication?

C G A T G T A

https://www.youtube.com/watch?v=z685FFqmrpo

Go to: Socrative.com Click on: Student login Type room XX7CWRJG

1. What is the result of DNA replication?

2. For each strand below, determine its complementary strand.

1. A A T C G G A T

2. T C G G T A A C

1. What are the steps in DNA replication?

1. What is the outcome of DNA replication?

1. Given the following strand of DNA, what would the complementary side read?

C T G A A T C G A

How does a cell grow and divide?

The Cell Cycle describes the life of a cell from birth to death

There are three main parts of the cycle:

▪ Interphase-Normal cell activities; broken up into 3 parts

▪ Mitosis-The process of cell division (1 cell becomes 2!)

▪ Cytokinesis-The division of the organelles and cytoplasm following mitosis

Interphase is indicated in grey-it is the longest phase of the cycle, broken into 3 parts

Mitosis is indicated in pink-we will discuss the stages of mitosis later!

G1 phase (Gap/Growth 1)-Period of cell growth▪ Cells can remain in the G1 phase

indefinitely▪ Called G0

S phase (Synthesis)-Period when DNA replication occurs▪ Once a cell copies its DNA, it must

divide▪ S phase allows daughter cells to have

exact copy of parent DNA after division!

G2 phase (Gap/Growth 2)-Cell growth and preparation for Mitosis

Mitosis is a form of asexual reproduction-means only 1 organism required

Occurs in response to the body’s need for growth and repair

4 stages of mitosis: Prophase, Metaphase, Anaphase, Telophase

▪ We’ll talk more about this in a bit!

The cell cycle ends with cytokinesis the division of the cytoplasm

▪ Accompanies mitosis

This means one cell has divided into two cells, and those two cells can continue with their own independent cell cycles!

http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html

Cyclins-Proteins that regulate the rate of the cycle

▪ Internal regulation-cell cycle can’t proceed until certain levels of these proteins are reached (ex. Poor nutrition cell stays in G1)

▪ External regulation-cycle can speed up or slow down

▪ Do you think a paper cut on your finger would cause the cell cycle to speed up or slow down?

Sometimes errors in the cell cycle can lead to cancer-▪ Errors can be genetic or due

to an environmental toxin Internal regulation error

followed by external; cells cannot “feel” their neighbors, and thus begin uncontrolled division ▪ Lack density dependence

(tumor) and anchorage dependence (metastasized cancer cells)

From 1: 15 https://www.youtube.com/watch?v=IeUANxFVXKc

1. Draw a simple diagram of the cell cycle, breaking it into the 4 main phases discussed today.

2. What is the purpose of cyclins within the cell cycle?

3. Explain why regulation of the cell cycle is so important to organisms.

1. Label the diagram on the right with the appropriate stage of the cell cycle.

2. At one point within the cell cycle, it divides. Why would cell division be necessary?

3. Explain how cancer is related to regulation of the cell cycle.

Cell Growth: Cell may stay indefinitely if it does not meet checkpoints

DNA is replicated.

Growth and preparation for division

Cell divides

Cytoplasm divides: 1 cell is now 2

Stages of Asexual Cell Division

Recall that the cell cycle is made up of three main parts

▪ Interphase (G1, S, and G2)

▪ Mitosis

▪ Cytokinesis

Mitosis refers to the division of the cell

▪ Asexual reproduction for unicellular eukaryotes

▪ Occurs in response to the bodies need for growth and repair

Occurs in eukaryotes 1 cell divides to produce 2 daughter cells These cells are identical to the original cell

same number of chromosomes!

What happens when the cell leaves interphase and is ready to begin division…?

What Happens?▪ Nuclear membrane dissolves

▪ Chromatin condenses into chromosomes▪ Chromatin: uncondensed DNA

(looks like spaghetti)

▪ Chromosome: condensed DNA (looks like X’s)

▪ Centrioles move to opposite ends of the cell

▪ Spindle forms and spindle fibers extend from one side to the other

What Happens?

▪ Centromeres (middle of chromosome) attach to spindle fibers

▪ Chromosomes are pulled to the middle of the cell

What Happens?

▪ Spindle fibers pull chromosomes apart

▪ Each sister chromatidmoves toward opposite end of the cell

What Happens?▪ Nuclear membrane

reforms

▪ Spindle fibers disappear

▪ Animal Cells: ▪ Cell membrane pinches

▪ Plant Cells: ▪ New cell wall begins to

form

What happens?

▪ Division of the cytoplasm and organelles

▪ 1 cell is now 2 identical cells!

INTERPHASE PROPHASE METAPHASE

ANAPHASE TELOPHASE

CYTOKINESIS

1. Draw and label the stages of mitosis. You should provide a brief explanation of what is happening beneath each stage.

Bellringer Day 06

1. Where is DNA located in Eukaryotic

organisms?

2. What is the purpose of DNA in organisms?

3. DNA is a nucleic acid. What is the other

nucleic acid?

4. Nucleotides are the building blocks of

nucleic acids. Draw and label a nucleotide.

DNA/RNATranscription and Translation

Review…

• DNA is responsible for controlling the production of proteins in the cell, which is essential to life–DNARNAProteins

• Chromosomes contain several thousand genes, each with the directions to make one protein

• Do you remember the organelle where proteins are produced?

Where are Proteins

Produced?

• Ribosomes!

• Ribosomes are where proteins are made

• Ribosomes are found in two places:

– Free floating in the cytoplasm

– Attached to Endoplasmic Reticulum (Rough ER)

• So…how does information needed to build the

protein get delivered from the DNA to the

ribosomes???

-With the help of RNA in a process called protein

synthesis!

What is RNA?

• RNA stands for ribonucleic acid

• One subunit of RNA is a nucleotide

(just like DNA!)

– 1 - 5 carbon sugar (it’s ribose in

RNA)

– 1 - phosphate group

– 1 – nitrogenous (N) base

• Three types of RNA

– mRNA, rRNA, tRNA

– First, we will look at mRNA!

A Closer Look: mRNA

• Looking at the mRNA to the right,

how is it different visually from DNA?

– It is single stranded

– It is shorter and able to leave the

nucleus

– The sugar is ribose

– There is a different base

• Uracil (U) takes the place of

Thymine (T)

About mRNA

• The job of mRNA is to take the

directions for one gene and

transport it to a ribosome in the

cytoplasm where it is translated.

– This is so the cell can begin

assembling amino acids, the

building blocks of proteins

– Like it’s name, it is sending a

message on how to do the job

– This is part of a process called

protein synthesis

A ribosome up close!!

Bellringer Day 07

1. List 3 differences you see between DNA and

RNA molecules.

2. Which organelle in cells is responsible for the

production of proteins?

3. In eukaryotes, DNA exists in the nucleus.

Hypothesize why RNA is necessary to carry

out the protein making process?

Protein Synthesis

• Protein synthesis is a two stages process

– Transcription and Translation

• In this process, a messenger molecule (mRNA)

carries instructions from DNA to ribosomes

– DNA cannot leave the nucleus!

– mRNA can!

• mRNA makes it possible for proteins to be

assembled by ribosomes outside of the nucleus

Protein SynthesisTranscription

Protein Synthesis:

Transcription

• Transcription happens when DNA is

turned into mRNA

• This happens when proteins need to be

made in the cytoplasm!

• Since DNA cannot leave the nucleus, it is

transcribed into RNA (DNARNA)

– Transcribe: to copy (copy in the same

nucleic acid language, but only copy what is

needed)

Protein Synthesis:

Transcription

• How does it happen?

– After an enzyme targets the portion of the DNA that

should be copied (initiation), the sections of DNA

(genes) will temporarily unwind to allow mRNA to

transcribe (copy). This will continue until an enzyme

signals “the end”

– mRNA leaves the nucleus, travels into the cytoplasm

and attaches to a ribosome

– The “message” from DNA can now be translated to

make a protein

Transcription

Practicing Transcription

• Transcribing DNA to mRNA is very easy if you

remember these complementary pairs!

– C (in RNA) will attach to a G (in DNA)

– G (in RNA) will attach to a C (in DNA)

– A (in RNA) will attach to a T (in DNA)

– U (in RNA) will attach to a A (in DNA)

• Try it!

A piece of DNA reads: T A G C A T T C C G A U

transcribe to mRNA:___________________________

Practicing Transcription

•If 1 side of DNA reads:

A A G C G T A T C C C G

•Then mRNA reads:

____________________________

Bellringer Day 08

1. Describe the steps taken during

transcription.

2. Transcribe the following to mRNA:

– AAT CGA TAG CCG ATA

3. What does it mean to translate something?

Protein SynthesisTranslation

TRANSLATION

• Translation: the process in which mRNA is

used as a blueprint to form chains of amino

acids (RNAProtein)

– Amino acids linked together form a protein

– Translate: To change a sentence from one

language (nucleic acid) to another (amino acid)

• Every 3 letters on an mRNA chain = codon

– Each codon (3 DNA letters) = 1 amino acid

Reading a Codon Chart

• Given the mRNA, we

can read a codon chart

to translated into the

amino acid it codes for

• Remember, 1 word in

nucleic acid language

is a codon (three

nucleotides)

Practice: Reading a Codon

Chart

• What amino

acid is coded

for?

– A U G

– G U C

– G C C

– C G A

– U A A

Protein Synthesis:

Translation

• Occurs in a ribosome

in ALL cells

• This process uses all

three forms of RNA

(mRNA, rRNA, and

tRNA)

• DNA is not directly

used!

mRNA

rRNA

tRNA

anticodon

AA (amino acid)

Steps of Translation

1.The mRNA leaves the nucleus and

lands on a ribosome (rRNA)

Steps of Translation

2. tRNA (with the correct anticodon)

lands on the ribosome opposite a

codon on the mRNA

tRNA: A Closer Look

Notice the tRNA is

carrying the amino acid

leucine, coded for by the

sequence “CUA” (check

your codon chart”)

The tRNA knows how to

match using bases! In RNA,

GC and AU:

So…mRNA codon reads

“CUA,” so the tRNA

anticodon will be “GAU”

tRNA: A Closer Look

anticodon

Amino acid

Steps of Translation

3. The tRNA leaves the ribosome, but

the amino acid that it coded for stays

on the ribosome to wait for next

codon to be read

Steps of Translation

4. The ribosome moves to the next codon

bringing in another amino acid to the

growing protein chain.

An Amino Acid Chain

• The amino acid chain will ALWAYS

begin with the “START codon”- AUG

• The tRNA will continue to add amino

acids until it reaches a “STOP codon”

(UAA, UAG, UGA)

• When it reaches a stop codon, then a

complete protein has been built! The

protein unattaches from the

ribosome.

DNA

molecule

DNA strand

(template)

3

TRANSCRIPTION

Codon

mRNA

TRANSLATION

Protein

Amino acid

35

5

Let’s practice…….

• Given the strand of DNA below, what would it’s

complementary DNA strand read?

ATC

• Now, transcribe the DNA to mRNA

• What amino acid does the codon code for? (use

codon chart)

• What would the anticodon on the tRNA read?

Try Again!

• Given the strand of DNA below, what would it’s

complementary DNA strand read?

TGA

• Now, transcribe the DNA to mRNA

• What amino acid does the codon code for? (use

codon chart)

• What would the anticodon on the tRNA read?

Day 04 – 2/3/17

• Given the strand of DNA below, complete the

following:

ATT GCT AGG TAA

• Transcribe the DNA to mRNA

• What amino acid are the codons coding for

during translation? (use codon chart)

• What would the anticodons on the tRNA read?

Protein Synthesis Activity

Bellringer Day 09

• Label the following: amino acid, mRNA, tRNA,

amino acid chain, ribosome, codon, anticodon

• Determine if this illustrates transcription or

translation.

6

7

Review: Protein Synthesis

• https://www.youtube.com/watch?v=2

zAGAmTkZNY

Protein Synthesis Review

• Use your whiteboards to answer the questions.

• Remember, you will have a quiz tomorrow on RNA

and protein synthesis!

1. DNA and RNA are both made up of subunits

(monomers) called what?

2. Draw and label a nucleotide.

3. There are numerous differences between DNA

and RNA. List 3 differences.

4. What are the two steps of protein synthesis

called?

5. True or false: DNA can leave the nucleus.

6. Transcription is the process of turning DNA into

________.

7. Transcribe the following DNA to mRNA:

ATC GGC AGC TTC AAG

8. What are the 3 types of RNA involved in

translation? Include what they stand for.

9. mRNA carries the directions for an amino acid.

Every 3 letters on the code is called a _______.

10. When mRNA leaves the nucleus, it lands on a

_________, which is responsible for making

proteins.

11. All strands of mRNA begin with AUG, which

means ______. The protein will continue to be built

until a ______ codon is reached.

12. Use your codon chart to translate the following

mRNA into amino acids:

AUG CCG AGG UGA UUG

Bellringer

Day 10

1. Label the

diagram of

protein

synthesis.

Quiz: Protein Synthesis

2009-2010

Mutations

Changes to DNA

Mutations

• Changes to DNA are called mutations

– These mutations change the mRNA code that

determines proteins

– This may result in no change, may change the

amino acid, or may change the whole protein!

• Mutations may be random, or they may be

caused by exposure to radiation/chemicals

Types of Mutations

• Substitutions:

– Change to one letter (base) in the DNA!

– Ex. A instead of T

– This may result in a different amino acid,

or it may be a silent mutation: no

change to the strand

Example: Sickle Cell Anemia

A substitution causes misshapen red blood cells.

Notice the change in the amino acid sequence?

Types of Mutations

• Deletion or Addition:

– A letter is added or removed

– Example: AACG instead of AAG

– This shifts the way the entire sequence

is read, resulting in an entirely new

strand of amino acids! This is a major

change to the protein, meaning it may

change the trait!

Heredity of Mutations

• Only mutations located in sex cells

(sperm and egg) can be passed on!

– For example, you could not inherit skin

cancer from a family member who

developed it after extensive UV

exposure.

Bellringer Day 11

1. Name and describe the main

types of mutations we talked

about yesterday.

2.Do mutations always cause a

change in amino acid? Why or

why not?

Bellringer Day 12

1.Explain the steps of protein

synthesis. You may write this in your

own words, but you should create at

least 5 steps to describe the process.

You may include as many steps as

you need. Be as detailed as possible.

Test: Day 13

• We will also be doing binder checks. Make sure

materials are in your binder in the correct order.