Biology Unit 4 Revision Packet Genetics Visual Notes

Biology (Unit 4) Revision Packet: Genetics Visual Notes Prepared by : Ms Sime

LABEL: Use the words below. chromosomes, chromatids, sister chromatids, centromere, replication

Crossing Over Meiosis

Use different colours to draw paternal and maternal chromosomes Label: chromatid, sister chromatids, chromosome Label: homologous chromosomes after S phase Diploid number: 2 n = How many chromosomes in the cell now? Synapsis Label: chiasma Crossing over (start) Label: recombinant chromatids Crossing over (end) What happens in Metaphase I ? In which phase does crossing over occur?

Meiosis Summary – Key Features Three unique features: 1. Synapsis: Pairing of homologous chromosomes Occurs after DNA replication. 2. Homologous recombination: Crossing over (genetic exchange/recombination of genes) occurs between homologous chromosomes. Crossing over during Prophase I Alters the linkage between genes on the same chromosome. 3. Reduction division: Omission of chromosome duplication before Meiosis II produces haploid gametes. Random orientation in Metaphase I

Linked Genes: A and B Does distance between two gene loci matter? Draw the outcome of crossing over Label: Parental chromosomes, recombinant chromosome

Recombinant chromosomes?

True or False: This phase occurs right after DNA replication. _______ Telophase II is likely to occur after this phase. _______ In this phase (Anaphase II), homologous chromosomes randomly orient themselves and segregate independently. _______ At the end of this phase, 4 haploid (n = 5) daughter cells should be produced. _______ The diploid number for the parent cell is 10. _______

GIRL or BOY? How many autosomes? How many sex chromosomes? Which pair is nonhomologous?

Definitions: Genotype: Phenotype: Give the phenotypes for: SS = Ss = ss =

How many alleles for wing colour? What are the alleles? Is the dark phenotype a dominant trait? How do you know?

Based on the punnet square below, what are the genotypes of the PARENTS? X

A test cross was used to find out the genotype of the parent with a dominant trait. What is a test cross? Give an example X Conclusion:

R = Red r = Black Monohybrid cross: Involves a single gene. How many alleles? Genotypic ratio: Phenotypic ratio: Is this phenotypic ratio expected for a monohybrid cross?

S = Smooth s = Wrinkly Y = Yellow y = Green Dihybrid cross: Involves a two genes. Genotypic ratio: Phenotypic ratio: Is this phenotypic ratio expected for a dihybrid cross?

Draw Punnet squares for the following crosses: 1) Normal female X Normal male 2) Normal female X Hemophiliac male 3) Hemophiliac female X Normal male 4) Hemophiliac female X Hemophiliac male 5) Carrier female X Normal male 6) Carrier female X Hemophiliac male

PEDIGREE BASICS Using the symbols, draw a pedigree for a family of three brothers and one sister. The female child is the only child that is affected. Both parents are unaffected. Can you predict the inheritance pattern for this pedigree? Inheritance pattern: ___________

Write possible genotypes for each individual in the pedigree on the right. Give 2 reasons that prove that the pedigree is showing an autosomal recessive inheritance. ______________________________ _______________

Write possible genotypes for each individual in the pedigree on the right. Give 2 reasons that prove that the pedigree is showing an X-linked recessive inheritance. ______________________________ _______________

Write possible genotypes for each individual in the pedigree on the right. Give 2 reasons that prove that the pedigree is showing an X-linked dominant inheritance. ______________________________ _______________

Write possible genotypes for each individual in the pedigree on the right. Give 2 reasons that prove that the pedigree is showing an autosomal dominant inheritance. ______________________________ _______________

Draw a single DNA nucleotide.

DNA Mutations Transcription Translation Primary structure of protein

DNA Mutations Transcription Translation Primary structure of protein

DNA Mutations Transcription Translation Primary structure of protein

DNA Mutations Silent mutations usually occur on the third base in a triplet. Explain why and give another example of a silent mutation for a different amino acid. Which of the mutations shown above are most detrimental? Explain.

DNA Mutations Describe the main idea that is conveyed in this diagram.

Central Dogma of Biology

Where in the cell does this process occur?

Gene structure: RNA processing 1. Circle the expressed regions in this gene.

What step in protein synthesis is shown here? Label the structures in the diagram. What are the functions of t. RNA and m. RNA?

The diagram on the left clearly shows that more than one codon codes for a single amino acid. What might this suggest about DNA? Use the codon table on the right to locate the amino acid coded for by: AUG and GAG Which codons do not code for any amino acids?