Inheritance and heredity

what is a hereditary trait

a characteristic that can be passed on from one generation to another

what is monohybrid inheritance

the inheritance of one characteristic, controlled by a single gene, that has two contrasting forms

Mendel’s model of heredity

1. Each trait is controlled by a pair of factors in cells

2. If the two factors are different, only the dominant factor will show its effect

3. The two factors separate during gamete formation and each gamete will only contain one factor

4. Random fusion of gametes → zygote formed contains two factors

wat is a locus

position on a chromosome

What arealleles

different versions of the same gene

Alleles occupy the same relative positions of a pair of homo chromosomes

what does homo chromos have in common in terms of loci

they have the exact same sequence of gene loci

what is a phenotype And what is it influenced by

its observable traits

genotype and environment

what is genotype

the genetic makeup of an organism which is inherited from its parents

what must you take note for a punnet square

• circle your gametes

preambles for a genetic diagram

1. Legend key: Let P be the dominant allele for… let p be the recessive allele for …

2. Parent phenotype: heretozygous… / homozygous dominant etc

3. Parental genotype: PP/ Pp …

4. Gametes (circles): P P P p

5. Random fertilisation: Punnett square / arrow diagram

6. Offspring genotypic ratio: 1PP, 2Pp, 1pp etc

7. Offspring phenotypic ratio: 3 dwar trait : 1 tall trait

8. Probability: 75% dwarf trait : 1 tall trait

how to conduct determine genotype

1. Test cross

2. Crossing the organism with a recessive organism

   1. If organism is homozygous dominant, all offspring should sow dominant trait as they are all hetero zygous dominant

   2. If organism is heterozygous, Hal the number of offspring should show the dominant trait, the other Half shows the recessive trait

co-dominance

alleles are heterozygous but both alleles are equally dominant and are both expressed

blending inheritance / incomplete inheritance

one allele for a specific trait is not completely dominant over the other allele

What are multipleallels

A gene for a particular trait exists in multiple alleles

What is mutatio

the sudden and spontaneous change in

1. Gene structure

2. Chromosome structure

3. Chromosome user

4. And may or may not be inheritable (inheritable NLB occuring in sex cells)

What happens in sickle cell anemia

1. Mutation in gene structure (its a recessive gene)

2. Cannot produce normal haemoglobin, replaces glutamic acid for valine

3. Faulty nucleotide → faulty plolypeptide sequence Affected the folding, shape and structure of haemoglobin

4. RBC becomes crescent shape

5. Abnormal Hb cannot transport oxygen effectively

Harm s and benefits of sickle cell anemia

harms — RBCs easily hooked onto one another → BV blockage // cannot transport O2 properly

Benefits — more resistant to malaria

1. Dont allow malaria parasites to reproduce effectively as thier nutrients leaks out of the stretched, porous cell membrane

what’s the down chromosome genotype and where did it come from

3 copies of 23

Unequal separation of homo chromos / sister chromatids during meiosis

Types of mutagens

1. Chemical

   1. Mustard gas, formaldehyde, ferrous, manganous salts

2. Radiation

   1. I light

   2. Alpha radiation

   3. Gamma radiation

   4. Beta radiation

why is mutation eneficial

essential for evolution to occur because they increase genetic variation and the potential for individuals to differ. It allows genetic variation to occur and organisms to evolve 

How may Mutation of good or bad

produce proteins with new or altered functions that can be useful to organisms in different or changing environments

Or

Result in protein production that disrupts biological functions and results in disease /cancer

Compare continuous and discontinuous variations

1. Phenotype: spectrum of phenotypes, ranging from one extreme to another VS a few clear-cut phenotype in distinct categories

2. Controlled: controlled by many genes VS a few genes

3. Additive effects: genes show additive effects vs no additive effects

4. Environment: modified by environment vs Un modified by environment

Significance of variation

1. Increases the chances of survival of the species. New offspring will be able to survive though new conditions either environmental or otherwise 

2. without variation, certain species face the danger extinction survival of the species. New offspring will be able to survive though new conditions either environmental or otherwise 

What is an adaptation

Any characteristic that increase fitness, which is defined as the ability to survive and reproduce

What is the survival of the fittest

1. Those that adaptation better to their environment survive better (be it predation or habitat)

2. Those who survive reprduce. Their heritable characteristics are influenced by genes and passed from surviving parent t offspring. New generations ill ted to contain a higher proportion of individuals suited to survival

3. The above is repeated over several generations, the characteristics become more commo / predominant in the population

4. EVOLUTION

what characteristic makes an organism considered fit

1. Long life space

2. Survive predation (camouflage)

3. High reprduction rate

what makes a trait become more prevalent after generations

1. High reproduction rate

2. High length of survival

what is the full process of natural selection

• Mutation brings about variation 

• variation has some effect on their chances of survival 

  • colour flour, running speed, sharper claws (better at digging the beach to look for food)

• environment in which they live in determines who survives better

• winner survive to reproduce. If variation is heritable, new generations will tend to contain a higher proportion of individuals suited to survival (Selection)

• Its is repeated over several generations, this characteristic becomes more common in the population

conditions for natural selection

1. Variation in characteristics

2. Difference in fitness

   1. Different characteristics must contribute to differences in fitness

3. Trait must be inheritable

   1. Characteristic that affect fitness must be able to passed by genes from one generation to the next