Day 2 The 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 chromosomes in the nucleus.
Each nucleotide is composed of: 1. Sugar (deoxyribose) 2. Phosphate group 3. 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-A C-G G-C T-A A-T DNA is the molecule that determines and organism’s eye color, body structure, and protein production.
Replication demo on PBS
T T C GC A A G 1. The hydrogen bonds holding the nitrogen bases together break apart.
T C G AT 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 RNA rRNA = ribosomal RNA tRNA = 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 sugars H Sequence of amino acids J 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 strand will 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: FF
Answer: A
Answer: J
Answer: C
TAK Obj. 02 TEKS B.6C Answer: J
TAK Obj. 02 TEKS B.6B Answer: A
#9 What are three differences between DNA and RNA? #10What are the three types of RNA? #11What 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
#12What is a codon? #13What does it “code” for? #14How 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
46 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 During metaphase, the chromosomes move to the equator (middle) of the spindle. Centromere Sister chromatids
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 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 23 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 condense the 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