Introduction to Biology Week 4

Agenda Sign in Turn in any late work and your homework now Notes and activities, Part II of Textbook Labs Homework

I am traveling for work this week. I’ll be back next week I am traveling for work this week. I’ll be back next week! Please turn in all your work that is due now. If you have questions, you may email me or wait until I return: jmarsico@swfc.edu

Chapter 8: Cellular Reproduction 8.1 The Basics of Cellular Reproduction Necessary for growth, replacing damaged tissues, and reproduction All cells come from cells Two processes: growth and cell division Today we are focusing on cell division and DNA.

DNA Replication: the copying of DNA DNA is packaged into chromosomes- proteins and DNA to be passed on to new cells DNA usually is in long, thin strands called chromatin Strands are wound tightly to form chromosomes Each species has a different chromosome number (humans have 46) When we see chromosomes, DNA has copied itself into two sister chromatids held together by a centromere The number of chromosomes will vary greatly from species to speices.

8.2 The cell cycle Cell cycle- orderly sequence of stages that takes place from the creation of a new cell to division of the cell Most of cycle is spent in interphase, when cell performs normal life functions, replicates its DNA, and grows in preparations for division Mitoic Stage- when division of nucleus and cytoplasm occurs

8.3 Mitosis and Cytokinesis Duplicated DNA is passed equally to daughter cells (new cells) Most cells require a spindle, or part of the cytoskeleton, to help separate chromosomes Divided into 4 phases: prophase, metaphase, anaphase and telophase

Daughter DNA is identical to parent DNA Cytokinesis is the splitting of the cell into two In animal cells, the cell pinches in with help of a contractile ring In plant cells, a cell plate forms between the two cells Note the two ways in which cells divide to form two new cells, it is different in plant and animal cells.

Here are the four basic steps of mitosis.

Chapter 9: Sexual Reproduction Meiosis- type of nuclear divison in which the chromosome number is reduced and chromosomes are shuffled to produce gametes (eggs and sperm)

Chromosomes occur in pairs (humans have 23 pairs) Males and females are different, the sex chromosomes (x and y) are different in males and females Other chromosomes are called autosomes Males are XY and females are XX Diploid number (2n) is 46 in humans; haploid number (n) is 23 Members of the pair are called homologous chromosomes

This is a Karyotype, or a picture of all the chromosomes in the cell This is a Karyotype, or a picture of all the chromosomes in the cell. This is for a male, because there are two sex chromosomes, x and y (females would be xx). Note that there are 23 pairs.

Zygote: fusion of egg and sperm during fertilization Consists of two divisions: Meiosis I and Meiosis II Because of meiosis, there are many possible combinations of chromosomes Crossing over may occur, resulting in the mixing of genetic information Importance: Keeps chromosome number constant when producing gametes Introduces genetic variations (crossing over and combinations) It is very important that the number of chromosomes remain constant from parent to offspring. Meiosis is the way nature ensures this occurs.

9.2 The phases of meiosis The phases are the same as mitosis, difference is in how chromosomes align

Internet Lesson- Mitosis and Meiosis Now that you know the basics for mitosis and meiosis… See the handouts for websites. Type them carefully. Answer the questions as you go. Turn in handouts when done. This lesson should help you learn to recognize the stages of mitosis and meiosis.

To recap: 9.3 Meiosis compared to mitosis Mitosis results in 2 daughters, meiosis in 4 Mitosis results in diploid cells, meiosis haploid In meiosis, tetrads align at the equator instead of chromosomes individually Meiosis occurs only in sexual tissues and only at certain times during the life cycle of organisms

This diagram shows the basic steps of mitosis and meiosis.

Create a Venn Diagram Comparing Mitosis and Meiosis Shared characteristics go in the center Use your textbook to help you Mitosis Meiosis Use your textbook to examine the characteristics of mitosis and meiosis, and fill in the sides of the Venn diagram. Characteristics that they share go in the center. You may want to write down the characteristics in a chart first, then combine them to make the diagram.

Chapter 10: Patterns of Inheritance 10.1 Mendel’s Law Gregor Mendel was an Austrian monk who developed laws of heredity by studying garden pea plants (this was before the processes of DNA were known) Peas were a good plant to study because they are easy to grow and have a short generation time as well as being self-pollinating. They can be pollinated by hand.

Used mathematical probability to explain his results Particulate theory of inheritance: existence of minute particles (now called genes) Parents are called P Generation, offspring are the F generation His discoveries are useful today, despite being very old.

We use Punnett squares to represent all the possible types of eggs and sperm and all the possible combinations of gametes the offspring can inherit. We now use the chromosomal theory of inheritance: dominant and recessive alleles (forms of a gene); homozygous (two same alleles) and heterozygous (two different alleles); genotype (alleles) and phenotype (expression/ physical appearance).

Law of independent assortment: pairs separate independently and all possible combinations are possible

This Punnett Square shows a cross between two pea plants and then the cross between two of the offspring plants.

How to do a Punnett Square One set of alleles goes on the top of the boxes The second set of alleles goes on the side You will practice this later in your virtual lab.

For example, pea plants may be… Dominant trait gets the capital letter; recessive the lower case letter Homozygous is two of the same letter; heterozygous is two different letters For example, pea plants may be… Tall with a TT genotype Tall with a Tt genotype Short with a tt genotype The first and last example are homozygous because they share the same letter

For a cross between… A heterozygous long haired rabbit and a homozygous recessive short haired rabbit L l l l The letters are filled in as they are above

To do the cross… Drop the top letter down and move the side letter over L l l l

The final cross will look like this: 50% of the offspring will be heterozygous long haired (Ll) 50% of the offspring will be homozygous short haired (ll) L l Ll ll l l

Chapter 11: DNA Biology and Technology 11.1: DNA and RNA Structure and Function Contains nucleotides: adenine (A); guanine (G); thymine (T); cytosine (C) Amount of A=T and amount of G= C Has a double helix shape Is double stranded Replication: process of copying DNA Each strand is used as a template to make a new DNA molecule with one old strand and one new strand

Here is a drawing and a model of the DNA molecule Here is a drawing and a model of the DNA molecule. You will be examining the molecule in more detail for homework.

RNA is made up of the same bases except T is replaced with uracil (u) and there is only one strand Instead of t there is u. There is only one strand. Otherwise they are very similar.

There are three types of RNA mRNA: made in nucleus and carries genetic information to the ribosomes for protein synthesis tRNA: made in nucleus and transfers amino acids to ribosomes to make proteins rRNA: produced in nucleolus in nucleus is used to form ribosomes There are three types of RNA: Messenger; Transfer and Ribosomal- or m, t, and r for short.

11.2 Gene Expression Transcription: DNA serves as a template for RNA formation Translation: mRNA bases determines sequence of amino acids in a protein Code is written in triplet, called a codon, which represents a amino acid Code is universal in all living things

Process of forming proteins: mRNA is formed from DNA (forms a complementary strand) mRNA is processed and leaves the nucleus to go to ribosomes tRNA brings amino acids to the ribosomes Ribosome connects the amino acids into a chain (protein) Here are the steps for making proteins from DNA.

Gene mutation: change in the sequence of bases in a gene due to error in replication or environmental mutagen (X-rays, radioactivity, UV light, chemicals, etc.) Sometimes there are mistakes in copying the DNA. Mutations may not be harmful, may be harmful or may sometimes be beneficial.

11.3 DNA Technology Genetic engineering: when a gene can be inserted into the genome of an organism Biotechnology: use of natural biological systems to create a product Transgenic bacteria, plants and animals Make vaccines, break down oil, faster/larger growth Can be use DNA fingerprinting for medical uses or to identify parents/children, solve crimes

Review The two identical halves of a duplicated chromosomes are called A) chromosome arms B) nucleosomes C) chromatids D) Homologues

A human cell contains ___ pairs of sex chromosomes A human cell contains ___ pairs of sex chromosomes. A) 1 B) 2 C) 22 C) 23

In Mendel’s particulate theory of inheritance, the “particles” are now known to be Chromosomes Genes Plants Pollen grains B) Genes

DNA replication is semiconservative because… Each new DNA contains one old strand and one new strand Each new DNA contains two new strands A) Each new DNA contains one old strand and one new strand

Virtual Labs www.mhhe.com/maderessentials2 Labs for today: Punnett Squares The Cell Cycle and Cancer

Homework Read chapters 14, 15 and 16 DNA Coloring Worksheet Complete Virtual Labs (if not done in class) Be prepared for a matching quiz on the terms: organism, osmosis, chromosomes, photosynthesis, cellular respiration, adaptation, prokaryotic, eukaryotic, mitosis, meiosis, replication, transcription, translation, zygote, mutation