Biostatistics in biology

Why we use biostatistics in biology

Facts should be proven e.g. Chemical A is anticancer drug. How to prove it?

Facts should be proven e.g. Chemical A is anticancer drug. How to prove it? Experimental design Experimental factors Control

Experimental design Measure for a pre-tested parameters such as markers Use prop Test Analysis ……..etc.

Experimental factors All experimental factors should be fixed except the drug E.g. Dose dependant Different extraction method of the drug Different administration of the drug Sample size of the experiment

Sample size Number of replicates tested

Control Positive control Negative control

Where is the correct value? variable R1: 30 R2: 26 R3: 36 R4: 48 R5: 50 R6: 16 R7: 31 Mean(Ý) =33.85 n=7

Statistical analysis

Standard deviation Degree of freedom =n-1

Biological data Aflatoxin in peanut ( Y) Y-Ý(Y-Ý) Mean(Ý) =33.85 n=7 =

Justify a genetic hypothesis using chi square test

Chi square test X2 = Also called ANOVA or X 2 test for goodness of fit Is observed data consistent with hypothesized ones?

Example for chi square test application in genetics In a cross between smooth and wrinkled pea seeds, you obtained 99 smooth seeds and 45 wrinkled seeds. Determine if the ratio 3:1 is consistent with this result.

Problem 1 Justify 3:1 ratio

Problem 2 Do you think the inheritance of the above genetic trait follows the ratio of 1:2:1

Problem 2 answer justify the ratio 1:2:1 GenotypeobservedexpectedO-E AA Aa aa Total

Types of variables 1- Qualitative 2- Quantitative

Arrange your data in a meaningful form 1- Data tabulation 2- Graph 3-Statistical analysis

Use of molecular genetic in genotyping

Genetic analysis Analysis of a certain genetic trait is very complicated. Researchers need to identify all genes responsible for phenotype determination as well as interacting genes. E.g. Cell shape genes and mutation induction methodology

Mutation induction to study a genetic trait X-ray Insertional mutagenesis Chemical mutagenesis

Complementation test in gene identification

Results interpretation