Genetics

Explain about structure of DNA, from DNA itself to nucleotide structure and polynucleotide strands

DNA= Double Helix, Long Strands, Stable (Not Easisly broken) Nucleotide=Phosphate,Pentose sugar (deoxyribose),Nitrogenous base (Adenine, Thymine, Cytosine, Guanine) G&C join together, A&T together, H Bond ,Nucleotides join by sugar-phosphate backbone

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What makes DNA great for strorage? How does it exist in Eukaryotic & Prokaryotic cells?

Eukaryotic cells = Long thread of DNA wound around histones Prokaryotic = Chromones shorter and circular, condenses by supercoiling Double helix - Stable (not easilsy broken) Coiled up tightly fits in small places, paired strucutre easier to copy

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How are proteins made using genes?

Proteins > Amino Acid Sequence >3 Genes (code on)(triplet) make 1 amino acid, sequence of genes make proteins. Degenerate code = more than 2 triplet mutiple of the same amino acid Exons r coding, introns non-coding, mutiple repeats 20 amino, 64 trip

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What are Alleles?

Genes in a different form, bases slightly different (slightly different version of same characteristic)

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What are the four steps leading from DNA Sequence to Metabolic Pathways?

DNA Sequence (detmines amino acid sequence) - > Proteins & Enzymes formed -> Enzymes control metabolic pathways - > Metabolic pathways help determine nature and development

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What are homologus chromosones?

23 pairs, 46 chromosomes. Matching pairs are homologus(same genes diff alleles) Alleles coding for same characteristic will on same place on each pair

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What are mutations?

Changes in base sequence, New alles of genes, can produce differnt or non-functional proteins, Enzymes may not fold up properly, changes active site making non-functional

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What are the Five stages of Meiosis?

Step1: DNA unravels and replicates (chromatids) Step2: DNA Condenses to form double armed chromosomes, sister chromatids Step3: Arranged into homologus pairs Step4: Meiosis 1->Homologus pairs seperated (halving chromosomes) Step five: Meiosis 2-> 4 h

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What is diploid and haploid?

Diploid = 2n, normal chromosomes in body, Gametes have haploid (just n)

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What are gametes?

Gametes are sperm cells in males, and egg cells in females. Join together at fertilisation. Produces zygote, divides into new orgasnism.

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How is genetic variation caused in Gametes?

1. Crossing over chromatids, twist around each other, bits of chromatids swap. Contains same genes but diff alelles. 2. Independent Segreation You have half chromosomes from mum (maternal) and half from dad (paternal) when gametes from combination

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What is the founder effect?

Few orgasnisms start new colony, few alles in gene pool, more inbreeding so higher genetic disorders, can occur due to migration

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What is a Genetic Bottleneck?

Big reduction in poplation reduces avaliable alleles in gene pool, larger population created from fewer individuals

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What are factors affecting increase & decrease in Genetic Diversity?

Increase, mutations in DNA - New allles, gene flow where different alleles move between populations where interspecific species sex happens. Decrease - Selective breeding , Founder Effect, Selective Breeding.

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What is selective breeding, and reasons for and against?

Best charactersitcs re-bred by humans. For: high yield in plant and animals, increase resistance to disease, Against : Health problems , Reduced genetic diversity.

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Genetics

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