Day 2The student will demonstrate an understanding of the organization of living systems.

DNA (Deoxyribonucleic Acid), carries all the

genetic information of an organism.

DNA is stored in the nucleus of a cell.

DNA packaged as chromosome

s in the nucleus.

Each nucleotide is composed of:

1. Sugar (deoxyribose)2. Phosphate group3. A nitrogen base

a. Adenine (A)b. Guanine (G)c. Thymine (T)d. Cytosine (C)

The nitrogen bases always bond in a very specific

manner.

A always pairs with T (AT&T)

G always pairs with C (GNC)

The bases are held together with a Hydrogen bond.

T-AC-GG-CT-AA-T

DNA is the molecule that determines and organism’s eye color, body structure, and protein production.

Replication demo on PBS

T

T

C

G C

A

A

G

1. The hydrogen

bonds holding the

nitrogen bases

together break apart.

T

C

G

A T

C

A

G

T

T

G

G

A

A

C

C

RNA is single stranded. It contains the sugar

is ribose.

The four nitrogen bases of RNA include:adenine (A)uracil (U)

guanine (G)cytosine (C)

A now pairs with U

There are 3 types of RNA involved in making

proteins:

mRNA = messenger RNArRNA = ribosomal RNAtRNA = transfer RNA

Messenger RNA (mRNA), copies the code from the DNA in the

nucleus and moves to the cytoplasm.

Transfer RNA (tRNA), carries the amino acids to the ribosomes

to assemble the proteins.

Ribosomal RNA (rRNA), puts the “message” together making

the proteins.

Transcription occurs when DNA is copied into an mRNA strand.

A codon is a group of three nitrogen bases. Each codon

represents a certain amino acid.

Translation occurs when a codon is used

to create an amino acid chain that

eventually becomes a protein.

It says codons, and has U instead of T, so it must be mRNA.

DNA TACAAACGACCGTTC . . .ATGTTTGCTGGCAAG . . .

↓ (1) DNA serves as a template from which mRNA(messenger RNA) is made.

mRNA AUGUUUGCUGGCAAG . . .↓ (2)

methionine + phenylalanine + alanine + glycine + lysine . . .

A An mRNA molecule signals which nucleotides should be joined to form a nucleic acid.B The codons of an mRNA molecule signal proteins to create a carbohydrate chain.C The genetic information coded in an mRNA molecule is translated into an amino acid chain.D A protein chain acts as a pattern for creating an mRNA molecule

with the proper sequence.

Which statement best describes the process at Step 2 in the diagram?

Answer: C

F Amount of adenine

G Number of sugarsH Sequence of

amino acidsJ Strength of

hydrogen bonds

This is only one of the 4 nitrogen bases, it can’t code for anything by itself.

Every nitrogen base is attached to a sugar, so this is not correct.

Hydrogen bonds strength does not change enough to code for trait changes.

H

3. If the template of a strand of DNA is 5' AGATGCATC 3', the complementary strandwill be —F 3' TCTACGTAG 5'G 5' CTACGTAGA 3'H 3' AGATGCATC 5'J 5' AGACGTCTA 3'

5' AGATGCATC 3‘

TCTACGTAG

Base pair each letter by the above rule.

So the answer is:

F

Answer: A

Answer: J

Answer: C

TAK Obj. 02TEKS B.6C

Answer: J

TAK Obj. 02TEKS B.6B

Answer: A

#9 What are three differences between DNA and RNA?

#10 What are the three types of RNA?

#11 What is the difference between transcription and translation?

1. The sugar

2. DNA is a double helix and RNA is single

3. There is no uracil in DNA and no thymine in RNA

mRNA, tRNA, rRNA

In transcription the code is being stolen and in translation they are tanslating the code into amino acids

#12 What is a codon?

#13 What does it “code” for?

#14 How do the bases in DNA pair up?

A three letter piece of the DNA that the mRNA stole

An amino acid

A with T and G with C

Mitosis and Meiosis

Cell division is the

process by which new cells are produced from one

cell.

Structures, which contain DNA and become darkly colored

when stained, are called chromosomes.

Chromosomes are the carriers of the

genetic material that is

copied and passed from generation to generation of

cells.

The cell cycle is the sequence of growth and division of a eukaryotic

cell.

• The majority of a cell’s life is spent in the growth period known as interphase.

Interphase

Following interphase, a cell enters its period of nuclear

division called mitosis.

Mitosis

Parent cell

Daughter cells

• The four phases of mitosis are prophase, metaphase, anaphase, and telophase.

Prophase

Metaphase

Anaphase

Telophase

The two halves of the doubled structure are

called sister chromatids.

Sister chromatids

• Sister chromatids are held together by a structure called a centromere, which plays a role in chromosome movement during mitosis.

Centromere

Metaphase: The second stage of mitosis

Metaphase: The second stage of mitosis

• During metaphase, the chromosomes move to the equator (middle) of the spindle.

Centromere

Sister chromatids

Anaphase: The third phase of mitosis

Anaphase: The third phase of mitosis

• During anaphase, the centromeres split and the sister chromatids are pulled apart to opposite poles of the cell.

Telophase: The fourth phase of mitosis

Telophase: The fourth phase of mitosis

• During telophase, two distinct daughter cells are formed. The cells separate as the cell cycle proceeds into the next interphase.

Nuclear envelope reappears

Two daughter cells are formed

Following telophase, the cell’s cytoplasm divides in a process called cytokinesis.

Four new cells are produced with half the

original number of

chromosomes in each.

46

23232323

Meiosis produces gametes, egg and sperm cells.

so that when the egg and sperm unite to form

the zygote, the zygote will

have the proper number of

chromosomes.

Meiosis is a form of cell division.

Meiosis is made up of 2 nuclear divisions.

The first is called Meiosis I, and the second is Meiosis II.

Prophase I – chromosomes

condensethe nuclear

envelope breaks down

the homologous chromosomes pair up.

This is the only place where crossing-over can occur. Prophase I

A unique event occurs during Meiosis:Crossing-over – while homologous chromosomes are paired, the arms of the chromosomes exchange segments of DNA They switch shoes

Metaphase I – the pairs of homologous chromosomes are moved by spindle fibers to the equator or middle of the cell.

Metaphase I

Anaphase I – the homologues separate, and each chromosome is still composed of two sister chromatids joined by a centromere.

Anaphase I

Telophase I – individual chromosomes gather at each end of the poles, the cytoplasm divides, forming two new cells.

Note that each new cell formed now has half the number of chromosomes of the original cell.

Meiosis I is called reduction division.

Telophase I

• The spindle is broken down, the chromosomes uncoil, and the cytoplasm divides to yield two new cells.

Meiosis 1

Meiosis 2

Mitosis produces cells with a complete set of chromosomes, identical to the parent

cell from which it divided. Meiosis produces gametes with only half the

original number of chromosomes.

Mitosis produces 2 new cells and meiosis results in 4 new cells.

#1 Sex cells undergo .

#2 What are the four phases of mitosis in order from first to last?

Meiosis

1.Prophase

2.Metaphase

3.Anaphase

4.Telophase

F 11 G 19 H 38 J 76

Mitosis is the normal division of any body cell, so the chromosomes replicate exactly and then separate into two identical cells. So the answer is

H