IB Biology HL 1: 3.1 & 3.2 Genetics

List 3 factors that increase the chance of genetic mutations

-Carcinogens -Non-disjunctions (chromosomes failing to separate resulting in extra or missing chromosomes) -Ultra Violet Rays

Outline the principles of sex determination

-Human have 23 pairs of chromosomes, the first 22 are autosomes. -The 23rd pair of chromosomes is called heterosomes, that determine gender. Females have 2 X chromosomes, while males have one X and one Y chromosome. -The male sperm containing either an X or Y chromosome determines which gender the person is. (Because the female always contains the X chromosome)

Define Allele

An alternative form of a gene

Identify parts of the world where a single sickle cell (Hb^s) allele could be beneficial:

Anywhere a malaria epidemic is occurring. Specifically: - Sub-saharan Africa - Latin America - Middle East - Parts of Europe

Define Chromatid

2 strands joined together by a single centromere

State the number of chromosomes present in a single human diploid cell

46 Chromosomes; 23 pairs of Chromosome

Define Gene

A heritable factor that controls a specific characteristic

Define Mutation

A permanent change in the base sequence of DNA formed from the duplication of the chromosome.

Outline the cause and effects of sickle cell anemia

Causes: A base substitution mutation is the change of a single base in a sequence of DNA. Resulting in a change to mRNA codon during transcription. The DNA sequence for hemoglobin is changed from GAG to GTG, thus changing the codon into a single amino acid -Valine. The change causes the blood cells to adopt a sickle shape. Sickle cell occurs when a person has 2 copies of the sickle cell allele Effects: The changed hemoglobin cannot effectively carry oxygen (tiredness), the sickle cells may cause clots and blockages, it also causes anemia because the sickle cells are destroyed rapidly, increased resistance malaria.

Define Diploid

Cells with a full set of chromosomes

Define Haploid

Cells with half of the total number of chromosomes

Identify the 2 structures of a chromosome in prophase-stage

Centromere and Sister Chromatids

State the components of a chromosome

DNA & Proteins

Outline how mutation lead to evolution by natural sciences

Different alleles in genes are variations within a species resulting from mutations. Natural selection occurs when that variation in allele or mutation is beneficial enough and useful enough to aid in the survival of the original mutation carrier. So the allele is then passed down the genetic slide and becomes a heritable characteristic within that species.

Compare and contrast prokaryotic and eukaryotic genomes. Compare and contrast viral prokaryotic and eukaryotic genomes and chromosome numbers

Euk: DNA is linear in eukaryotes DNA in eukaryotes is bound with histones Prok: DNA in prokaryotes have no histones DNA in prokaryotes is circular Chromosome Numbers vary by species. Prokaryotes divide by binary fission

Give two examples of genes and some of their possible alleles

Gene--------------------> Alleles Eye Colour---->Blue, brown, green, hazel Hair Colour of Mice--->Black, brown, agouti, gray, albino

Explain why a Sickle Cell allele could be beneficial where Malaria is

Malaria is spread through mosquitoes and into a persons blood cells with an anti-coagulating saliva with plasmodium. The blood cells affected by a sickle cell allele have abnormal hemoglobin that hardens the blood cell enough so as to not be harmed by malaria.

Using a punnett square, show why we expect an equal number of boy and girl babies to be conceived.

Males have an X, Y chromosome Females have X, X chromosome Thus (XX)^2 and (XY)^2; so theres a 50/50 chance of both genders being produced.

Summarize the process, results and significance of the Human Genome Project.

Process- Anonymous blood samples were taken, it was a collaborative research project to sequence the whole genome, clone libraries (clones of certain segments of DNA) so that any scientist could access it, they stored the clones in e.coli which allowed the clone libraries to be tracked and easily copied. The products were fed into an automatic sequencing machine that arranged the DNA sequences in its proper order. Results- The results were 99.9% accurate, project was finished by 2003, it ended up being 3 billion letters. Significance- Able to draft other (mouse) genomes later, also able to identify 100+ of human diseases, and the 100 diseases became 1,400. Gave rise to bioinformatics, with a high tech way to access genetic databases.

Outline how the spread of sickle cell genes is an example of natural selection in action.

Sickle Cell disease, when only in one copy can be used to prevent Malaria. An adaption that can be passed on to children. 2 copies--> Anemia, possible death

Describe how karyograms are made and what information they can provide

Stop the growth of the chromosome during metaphase and then staining the chromosome, and then photographing the chromosomes with a microscope and then arranging them in pairs. The karyotype gives information about the number of chromosomes a person has, the structure of their chromosomes and the sex of the individual. Karyotypes can help diagnose things like down syndrome which is characterized by 3 copies of the 21st chromosome.

Define Evolution

The cummulative changes in heritable characteristics of a population.

Define Gene Locus

The specific location of a gene on a chromosome

Define Geneome

The whole of the genetic information of an organism, cellular organelle

Define Chromosome

Thread-like structure of nucleic acids and proteins, carrying genetic information in the form of genes

Compare the 'Nonsense Mutation' and answer the following questions: a.) What is the number of bases substituted? b.) What effect does the mutation have on polypeptides? c.) What illness does the mutation make?

a.) 1 base is substituted b.) Stop codon produced early- polypeptide shortened c.) Cystic Fibrosis

Compare the 'Mis-sense Mutation' and answer the following questions: a.) What is the number of bases substituted? b.) What effect does the mutation have on polypeptides? c.) What illness does the mutation make?

a.) 1 base is substituted b.) The change in base sequence has caused 1 different amino acid to be produced c.) Sickle Cell Disease

Compare the 'Silent Mutation' and answer the following questions: a.) What is the number of bases substituted? b.) What effect does the mutation have on polypeptides? c.) What illness does the mutation make?

a.) 1 base is substituted b.) The change in base sequence has no effect on the amino acids produced. c.) Mental Disorders are prevalent in relation to the Silent Mutation

State three visual aspects of homologous chromosomes which can be used to identify

a.) Banding Patterns b.) Chromosome Size c.) Centromere Position

Describe the effects of sickle cell disease on sufferers in terms of: a.) Hemoglobin Production b.) Symptoms and Mortality

a.) Sickle cell disease is the result of a change in a single base sequence that produces valine instead of the original glutamine. The change in base sequence leads to the production of abnormal hemoglobin in red blood cells, that makes them harden (and become crescents if the mutation is strong). If a person inherits 1 copy of the faulty gene, the person is fine, if a person inherits 2 copies of the faulty gene then the abnormal hemoglobin is produced and the person runs the risk of blood clots due to the hardened crescent blood cells. b.) Symptoms: -Anemia -Fever -Dehydration -Dizziness -Fatigue -Organ Dysfunction -Pain Mortality can occur if the person experiences severe anemia or kidney failure.