Unit 5 : Cell Growth and Reproduction Lesson 1: Genes and Proteins Synthesis

Objectives: Genes and Protein Synthesis The Cell Cycle, DNA Replication, and Mitosis Genes, Alleles, and Meiosis

DNA Deoxyribonucleic acid Blueprint for building proteins. Monomers: nucleotides (sugar, base, phosphate group)

Bases Bases of DNA are: Adenine (A) Cytosine (C) Guanine (G) Thymine (T) DNA is a double stranded molecule. Adenine bonds with Thymine Cytosine bonds with Guanine

Codons Group of three nucleotides is called a codon. The sequence of nucleotides determines what amino acid will be added to make a protein. A region of DNA that codes for a protein is a gene. *Remember the monomer of protein is an amino acid. Gene expression: The process by which genetic information is used to make a protein.

Chromosomes DNA winds around proteins called histones, which coil and condense to make chromosomes. Prokaryotes have DNA that winds into a circle.

One strand of DNA contains the base sequence ACGGTATCG. What base sequence does the complementary strand contain? CTAAGCGTA ACGGTATCG TGCCATAGC GCTATGGCA

Transcription DNA is copied and a “transcript” of the information moves out of the nucleus into the cytoplasm in order to be read to make a protein. The “transcript” (or copy of DNA) is called RNA. RNA is only single stranded and has Uracil instead of Thymine.

Transcription cont. RNA (ribonucleic acid) Transcription : process when DNA is copied into a strand of mRNA. (messenger RNA) Steps to Transcription: 1. protein separates the two strands of DNA. 2. One strand of DNA is transcribed into mRNA. 3. RNA polymerase (protein) attaches the correct RNA nucleotide to build the strand of mRNA.

Transcription video https://www.youtube.com/watch?v=ztPkv7wc3yU

Translation There are 20 different amino acids that make up proteins. The order of amino acids in a protein determines the protein’s 3-d structure and function. Translation: process of making proteins from mRNA. Proteins are made in the cytoplasm on a ribosome.

Translation cont. Ribosomes contain rRNA (ribosomal RNA) and protein. Steps to Translation: 1. mRNA attaches to a ribosome. 2. The ribosome reads the mRNA and tRNA (transfer RNA) will transfer the correct amino acid onto the chain to build a protein. 3. The anticodon is the region on tRNA that is complementary to the codon found on the mRNA. Ex. UGG is the codon for the amino acid tryptophan. A tRNA molecule that binds to tryptophan has the complementary anticodon sequence ACC.

Translation cont. There are “start” codons and “stop” codons that helps the tRNA determine where to start building a protein and where to stop.

Translation video https://www.youtube.com/watch?v=-zb6r1MMTkc

Question Amino Acid Anticodon Serine AGA Valine CAA Leucine GAU What mRNA sequence was used to make a polypetide strand of serine, valine, and leucine?

Protein Synthesis in the Cell Proteins are made on ribosomes. Ribosomes are either attached to the ER or are free floating in the cytoplasm. If the protein is being made for the plasma membrane they will be made on the rER. If protein is being made for the cell to use they will be made on free ribosomes. The protein made on rER will be packed into vesicles. These vesicles will travel to the Golgi Apparatus, then will be modified and sent to the cell membrane.

Question Which organelle is not involved in the synthesis and secretion of a protein from the cell? A. Ribosome B. Smooth ER C. Golgi apparatus D. Plasma membrane

Keystone Packet Complete ques. 1-6 Pg. 112 & 113

Lesson 2: The Cell Cycle, DNA Replication, and Mitosis Cell cycle: the life cycle of a cell. 3 main stages: Interphase – G1, S, G2 (growth, DNA replication) Mitosis – nuclear division Cytokinesis – splitting of the cytoplasm

DNA Replication Produces an identical copy of each chromosome arm. Sister chromatid – each arm of a chromosome Centromere – center of chromosome that holds the two sister chromatids together.

DNA Replication During the S phase of Interphase the DNA replicates so that each daughter cell has a full set of DNA. Steps: DNA helicase separates the two strands of DNA DNA polymerase pairs up new nucleotides to each side of the DNA. Each new double strand contains one strand that came from the original DNA and one newly made.

DNA replication video https://www.youtube.com/watch?v=dKubyIRiN84

Mitosis Prophase: The nuclear membrane breaks down DNA coils up Centrioles begin to move toward the poles of cell

Metaphase: Centrioles produce spindles Spindles attach to the centromeres The chromatids line up along the center of the cell.

Anaphase: Spindles shorten The chromatids pull apart and move toward opposite poles of the cell.

Telophase: Nuclear membrane reforms The chromosomes unwind and become longer and thinner. Cytoplasm pinches

Cytokinesis Cell membrane pinches in center and two cells are formed.

homework Pg. 120,121 – Keystone Packet Lesson 2 Ques: 1-4 Crash Course – DNA Replication https://www.youtube.com/watch?v=8kK2zwjRV0M

Lesson 3 – Genes, Alleles, and Meiosis Review: mitosis – process in which the body grows and repairs itself. Meiosis – occurs in organisms that reproduce sexually, produces gametes (sex cells: sperm or egg cells). Chromosomes: coiled up DNA, humans have 46 chromosomes (23 pairs)

Homologous chromosomes Your chromosomes are grouped as homologous pairs. You have one side of the pair from your mom and the other from your dad.

Allele On each location there is a gene but different versions of the gene on each chromosome. Allele – version of “flavor” of a gene. In your body cells you have two alleles for each gene. In sex cells you have only one allele for each gene.

Sex cells Sex cells contain half the set of chromosomes. They are called haploid cells – half the set of chromosomes. n Diploid cells – contain the full set of chromosomes. 2n n = 23 pairs 2n = 2(23) = 46 chromosomes.

Meiosis Before Meiosis starts the cell has gone through interphase. During interphase the DNA is duplicated so the cell has two sets of 23 pairs. Two divisions to Meiosis: Meiosis I – one cell divides into two cells. Each cell is 2n. Meiosis II – two cells divide into four cells. Each cell is n.

Meiosis I Crossing –over : this occurs during Meiosis I. The homologous pairs cross their chromatids and exchange DNA. This occurs so that the egg or sperm cells are genetically diverse.

Phases of Meiosis Prophase I – the nuclear membrane breaks down. Chromosomes coil. Crossing-over occurs

Metaphase I Chromosomes line up in middle. Chromosomes are in pairs called tetrads. Spindle fibers attach to centromeres.

Anaphase I - spindles shorten The pairs of homologous chromosomes separate.

Telophase I Nuclear membrane reforms. Then cytokinesis occurs and end result is two 2n cells (diploid).

Prophase II The chromosomes condense again. New spindles form

Metaphase II The chromosomes line up in middle of cell. Spindle fibers attach to centromere.

Anaphase II Spindles shorten. Sister chromatids separate (just like in mitosis).

Telophase II Chromosomes uncoil. Nuclear membrane reforms. End result: 4 haploid (n) cells. Genetically diverse.

Differences between Mitosis and Meiosis