4.1 Living Things Inherit Traits in Patterns

Mrs. LeosApril 18, 2023

SO FAR……

We have learned that:Cells contain chromosomes

NOW we will learn about:How genes for traits are passed from parent to

offspringMore about Gregor MendelDominant and recessive alleles

Genetics

The study of gene structure and the patterns of inheritance of traits from parent to offspring.

Traits

Inherited Hair color, eye color, blood type Traits passed from parent to child

Acquired Ability to read, skills learned

GenesMade of DNA

Control traits that show up in an organism

Sections of the chromosome shown here have been coloured in. Each section is a piece of DNA called a gene.

HeredityPassing of traits (genes) from parent to offspring

Allelesalternative forms of the same gene

Each allele occupies same position on length of chromosome

Gene for hair color, allele could be blonde, brown or red

Multiple Alleles

A trait is controlled by more than two alleles Blood Type A&B =AB

Curly hair & straight hair= wavy hair

Brown Eyes & Green Eyes =Hazel eyes

Alleles are considered to be co-dominant

Co-dominant-both show up

Human Chromosome Number

46

Sex Chromosomes

X-chromosomeY Chromosome

XX=GirlXY=Boy

Gregor Mendel- Father of Genetics

Science of how trait are inherited through alleles

1856 studied garden peas for height, flower and pod position, seed shape, seed color, pod shape, pod color, flower color

Mendel SuccessMendel figured how traits were transmitted from parent to offspring.

He did not know about DNA, genes or chromosomes

PhenotypeActual characteristics that can be observed

Physical trait that show up

Examples:Height, size of feet

How something looks

Pheno=photo

GenotypeThe genetic makeup of an organism, all the genes that an organism has

Geno=gene

Genotype not always obvious

Principle of Dominant

Dominant Allele -form that appears or shows up

Covers up weaker form

Recessive Allele –expressed in phenotype only when two copies of it are present in the genotype

Form that seems to disappearStill carried by parent!!

On page 18

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