Chapter 14

Questions :

What is taxonomy and why do we use it ?

Taxonomy is the branch of biology that names and classifies species. We can either classify organisms based on their phenotypical features or based on their ecological role or we can recognize species that represent specific evolutionary lineage. We use taxonomy to make order and to observe similarities and traits of in

terest throughout the history.

What is sympatric speciation ?

Sympatric speciation - new species arise within the same geographic area as parent species. This speciation is very important. There have been many issue when people brought species from different countries into new environment which cause issue to the natural environment. That's why new species arise only within the same geographic area. They have natural environment there and also natural predators and food to consume.

What is prezygotic barrier ?

Prezygotic barrier prevents mating or fertilization between species. There are main five types : temporal isolation, habitat isolation, behavioral isolation, mechanical isolation and gametic isolation. Animals have these barriers to prevent closely related species from interbreeding.

Diagram :

This diagram shows an example of taxonomy. We list species in specific order which helps us to recognize where the animals belong and their closely relates species.

5facts:

Groups isolated by diet or female mate choice may have lost the ability to interbreed.

Every time speciation occurs, the diversity of life increases.

Carolus Linnaeus developed binomial system naming of organisms.

The process of speciation depends on whether reproductive barriers prevent gene flow between populations.

The occasional hybridization between finch species introduces new genes into both populations.

Key terms :

reproductive barrier - biological feature, to prevent individuals of closely related species from interbreeding

temporal isolation - prezygotic barrier (PB), occurs when species breed at different time

habitat isolation - PB, two species live in the same general area but not in the same kinds of places

behavioral isolation - PB, there is little or no sexual attraction between females and males of different species

mechanical isolation - PB, female and male sex organs are not compatible

gametic isolation - PB, gametes of two different species do not unite to form a zygote

allopatric speciation - populations are separated by geographical barrier

polyploid - cells have more than two complete sets of chromosomes

hybrid zones - regions in which members of different species meet and mate

adaptive radiation - evolution of many diverse species from a common ancestor

Video :

Speciation

Summarize:

Chapter 14 continues to describe the process of evolution. Although this time the chapter more concentrates on speciation of species and different barriers that prevent species from interbreeding. The chapter also talks about hybrids and their process of evolution.

Chapter 13

Questions :

What are fossils and why do we need them ?

Fossils are preserved remains or traces of animals, plants and other organisms from past. We use fossils to date the different periods in Earth's life evolution. They are essential prove of Darvin's evolution theory.

Who is Darwin and where did he travel ?

Charles Darwin is an English naturalist. He established what we know today as an evolution theory. He published his theory with evidence in 1859 in book called On the Origin of Species.

His most known research comes from Galapagos Islands even though he traveled throughout the world to acquire his evidence.

What is adaptation ?

Adaptation is evolutionary process whereby a population becomes better suited to its habitat. This process takes place over many generations. It's also one of the basic phenomena of biology.

Diagram :

This diagram shows an example of evolution and natural selection in a specific animal specie.

5facts:

Individuals do not evolve, populations evolve.

Natural selection can amplify or diminish only heritable traits.

Evolution is not goal directed and does not lead to perfection.

Living organisms are adapted to their environment.

Favorable traits accumulate in a population over generations.

Key terms :

extinction - irrevocable loss of species

fossil record - sequence in which fossils appear within layers of sedimentary rocks

strata - rock layers

paleontologist - scientist who studies fossils

homology - similarity in characteristics resulted from common ancestry

vestigial organs - structures of marginal or perhaps no importance to the organism

population - group of individuals of the same species

mutation - change in the nucleotide sequence of DNA

gene pool - total collection of genes in a population at any one time

sexual selection - form of natural selection in which individuals with certain characteristics are more likely than other individuals to obtain mates

Video :

Sexual selection

Summarize :

Chapter 13 introduce deeper informations about Darwin's theory of evolution and little bit of history behind this big scientific theory. Also we learned about fossils and their study. Since we talked in this chapter about Darwin we also talked about evolution theory and learned some new terms. For example Hardy-Weinberg equation etc.. At the end we learned mechanisms of microevolution.

Chapter 12

Questions :

What is forensics ?

Scientific analysis of evidence for crime scene investigations and other legal proceedings. Forensics involves DNA identification, finger prints etc...

Why do we need forensics ?

Forensics helps us to validate people that were at the crime scene. Due to forensics we can identify people's DNA and thus have a better evidence in solving the crimes. The first time DNA technology was used to solve a crime was in 1986 by Alec Jeffreys.

Diagram :

This diagram shows how gene therapy can help treat certain diseases by altering viruses DNA so it helps the body to heal.

5facts:

Vaccine is harmless variant of a pathogen, used to mount system against that pathogen

Genetically modified organisms are ones that required one or more genes by artificial means

STR analysis is a method of DNA profiling that compares the lengths of STR sequences at specific sites

PCr method is use to amplify DNA sequences.

Recombinant cells and organisms can mass-produce gene products that later on are used to treat certain diseases

Key terms :

plasmids - small circular DNA molecules that replicate separately from the much larger bacterial chromosome

genomic library - DNA fragments from a genome

vector - gene carrier

transgenic organism - recombinant organism

DNA profiling - analysis of DNA fragments

primers - short chemically synthesized single-stranded DNA molecules with sequences that are complementary to sequences at each end of the target sequence

genomics - science of studying a complete set of genes

transposable genes - genes that can move or be copied from one location to another

repetitive DNA - DNA that consists of nucleotide sequences that are present in multiple copies

Video :

Forensics

Summarize :

This chapter gave us an overview of different uses of genes. We can either solve crimes, modify plants and animals, categorize genes etc.

Chapter 11

Questions:

What is operon ?

It's a unit of genetic regulation common in prokaryotes; cluster of of genes with related functions, along with the promoter and operator that control their transcription.

How is DNA packed ?

Crucial role in DNA packing play proteins called histones. They protect packed DNA from being expressed. Also the DNA itself is wrapped around these proteins in formations called nucleosome.

What is cloning ?

Cloning is a process of creating new individual with genetic informations same as from the donor. There are two types of cloning : reproductive and therapeutic. Reproductive cloning creates a new individual with the same genetic informations as the donor. Therapeutic cloning uses embryonic stem cells to create specialized cells that are needed.

Diagram :

This diagram shows the process of cloning.

5facts:

Female mammals have one inactive X in each somatic cell.

Cascades of gene expression direct the development of an animal.

Stem cells are cells with no specialization.

Stem cells have a great medical potential.

Human reproductive cloning raises a lot of ethical issues. For example : to get stem cell we have to destroy embryo which in some cultures represents life.

Key terms :

gene expression - process by which genetic information flows from genes to proteins

histones - small proteins associated with DNA packing

differentiation - process of becoming specialized in function and structure

silencers - DNA sequence that stimulates the gene transcription

enhancers - DNA sequence that functions to inhibit the start of gene transcription

homeotic gene - master control gene

DNA microarray - glass slide with thousands of different kinds of single-stranded DNA fragments

regeneration - regrowth of lost body part

adult stem cells - cells capable of giving rise to many but not all the types of cells

oncogene - gene that can cause cancer

Video :

Nuclear transfer

Summarize :

This chapter was mainly about gene expression. The way genes are turned on a off and also this chapter described the process of cloning.

Chapter 10

What is DNA ?

DNA is genetic material. This fact was proved by Hershey and Chase. They did an experiment with bacteriophages in 1952. They labeled proteins and DNA by radioactive material. Due to this experiment that radioactively labeled DNA entered the host cell not the protein. This discovery supported the theory that DNA is radioactive material.

What is DNA and RNA composed of ?

DNA and RNA strands are called polynucleotides. Nucleotide is the basic unit. It's composed of phosphate group, sugar (ribose for RNA, deoxyribose for DNA) and nitrogenous base. There are 5 types of nitrogenous bases : Thymine, cytosine, adenine, guanine (these four can be found in DNA) and uracil (instead of Thymine there's an uracil in RNA).

How is DNA expressed ?

To have the genetic information expressed DNA must go through process of transcription and translation. During transcription DNA is transcribed into RNA molecule. Translation then translated those molecules into polypeptide chain.

Diagram :

This diagram shows a structure of DNA. Double-stranded helix and it also shows base pairing. with hydrogen bonds.

5facts:

DNA was proved to be genetic material in 1952 by Hershey and Chase.

Thymine (Uracil) pairs only with Adenine.

Guanine pairs only with Cytosine.

Watson and Crick were first to create the model of DNA.

Thymine and Cytosine are called Pyrimidines and Adenine and Guanine are called Purines.

Key terms :

bacteriophages - bacterial viruses

nucleotides - chemical units composed of nitrogenous base, phosphate group and sugar

double-helix - presence of two strands

semiconservative model - half of the parental DNA is maintained in each daughter molecule

DNA polymerase - unravels the DNA strand

DNA ligase - links the DNA strands back together

transcription - transfer of genetic information from DNA into RNA molecule

translation - transfer of the information in the RNA into a protein

genetic code - set of rules giving the correspondence between codons in RNA and amino acids in proteins

promoter - specific binding site for RNA polymerase

Video:

DNA transcription and translation

Summarize :

Chapter 10 give us an overview of the history of discovering the DNA and also the composition as well as its function and the way it functions, replicates and expresses genes.

Chapter 9

Questions :

What are Mendel's four hypothesis ?

There are alternative versions of genes that account for variations in inherited chracters.

For each character, an organism inherits two alleles, one from each parent.

If the two alleles of an inherited pair differ, then one determines the organism's appearance and is called the dominant allele,the other has no noticeable effect and is called and is called the recessive allele.

A sperm or egg carries only one allele for each inherited character because allele pairs separate from each other during the production of

gametes.

How technology helps find the chromosomal disorders ?

Due to new technologies we are to get tested for chromosomal disorders. For examples fetal testing, during which the doctor is able to detect harmful genetic conditions of the child, such as Down syndrome etc.... This testing is very helpful because our recessive alleles don't show themselves until we passed them on then they might have chance to affect the genes which could cause some harmful effects.

What is the difference between phenotype and genotype ?

Phenotype is genetic composition that is expre

ssed by organisms. This could be eye color, shape of nose, skin color etc.. On the other hand genotype is the genetic information that is inside the DNA. These are the traits that we're not able to see but we can pass them on and they could show in the next generation.

Diagram :

This diagram shows Punnett square. This square helps to discover the genetic combination if you have two heterozygous plants reproduce.

5facts:

Sex-linked disorders affect mostly males.

One single gene is capable of affecting many phenotype characters.

Environment we are living in may affect many characters.

We have two types of disorders recessive cause by the recessive gene and dominant disorders cause by the dominant gene.

Punnett square shows the possible gene combination based on the Mendel's hypothesizes

Key terms :

Alleles - alternative versions of a gene

Homozygous organism - organism that has two identical alleles

Heterozygous organism - organism that has two different alleles

Phenotype - organism's physical traits

Genotype - organism's genetic traits

Character - heritable feature

Trait - variant for a character

Hybrids - offsprings of two different varieties

Complete dominance - the dominant allele had the same phenotypic effect whether present in one or two copies

Incomplete dominance - some character's phenotype falls between two parental varieties

Video :

Punnett square

Summarize :

Chapter 9 gives a lecture about genetic informations and how are genes inherited. It describes Mendel's hypothesis and Punnett square which shows us the probability of inherited factors.

Chapter 8

Questions:

What are the phases of mitosis ?

First is interphase which lasts the longest time (about 90% of cell's life cycle) during this phase cell performs normal actions. Also this p

hase is divided into 3 sub-phases G1, S (division of DNA), G2. After interphase prophase follows. During prophase cell looses the nucleus and chromosomes become visible. Then there's prometaphase during this phase spindle is created. At metaphase chromosomes align on the metaphase plate. Then during anaphase the chromosomes separate and move toward the pole's of the cell. Telophase is finishing up the division and cytokinesis divides cytoplasm.

What is the difference between cytokinesis and mitosis ?

Cytokinesis represents the process of cytoplasmic division. Also during cytokinesis the cell finally separates into two daughter cells. On the other hand mitosis represents only the division of nucleus and chromosomes.

What is the difference between the products of Mitosis and Meiosis ?

The main difference between the products of Meiosis and Mitosis is that Meiosis produces cells with haploid number of chromosomes (23 for humans); Meiosis leads into creation of four daughter cells not two and these four cells are sex cells (sperm and egg).

Diagram:

This diagram shows Mitosis. The process and sub phases of Mitosis are described in Question 1.

5facts :

Mitosis is cell division.

Due to cross overs during Meiosis the daughter cells have different genetic variation than parent cells.

Meiosis produces four haploid cells and mitosis produces two diploid cells.

Karyotype is display of magnified images that helps the doctor diagnose any chromosomal diseases.

Down's syndrome is one of the most common chromosome number abnormality.

Key terms :

Karyotype - display of magnified images of an individual's chromosomes

Genetic recombination - the production of gene combinations different from those carried by the original chromosomes

Diploid cells - cells with two homologous sets of chromosomes

Haploid cells - cells with a single chromosome set

Fertilization - process when egg and sperm fuse together

Zygote - the resulting fertilized egg

Sex chromosomes - X and Y chromosomes

Autosomes - 22 pairs of chromosomes (sex chromosomes are not included)

Somatic cell - typical cell in human body

Tumor - an abnormally growing mass of body cells

Video :

Mitosis

Summarize : Chapter 8 was presenting Mitosis and Meiosis. The process of cell reproduction and also the abnormalities that can arise from mistakes during the cell division.