Unit 4: Inheritance Flashcards
Define GENOTYPE:
the GENETIC CONSTITUTION 📜 of an organism - the alleles an organism has
what’s meant by the “F2 generation” aka F squared
the SECOND set of offspring
Define HOMOZYGOTE:
organism that carries TWO copies of the SAME allele e.g. bb
Define HETEROZYGOTE:
organism carries two DIFFERENT alleles e.g. Bb
What does it mean if a characteristic is said to be SEX LINKED?
the ALLELE that codes 📲for the characteristic is carried on a SEX CHROMOSOME 🍆
Define GENE
a SEQUENCE 🌊 of BASES on a DNA MOL that codes 📲 for a PROTEIN (polypeptide) which results in a characteristic 👱
two genetic disorders caused by sex linkage:
- Haemophilia 💔
* Colour Blindness 😎
Blood Group Alleles:
Ia
Ib
Io
rank them in hierarchy of dominance
Ia and Ib co dominant
Io is recessive
What does a Genetic Pedigree Diagram show?
An INHERITED TRAIT in a group of RELATED individuals
How is Cystic Fibrosis caused?
Faulty RECESSIVE allele
Define GENE POOL 🏊
the complete RANGE of ALLELES present in a POPULATION
Define Allele Frequency
How OFTEN an ALLELE occurs in a POPULATION
What does the Hardy-Weinberg principle predict?
the FREQUENCY of ALLELES in a POPULATION remains CONSTANT one generation to the next 👴 ➡️ 👶
Criteria for the Hardy Weinberg principle to be true:
- NO mutation
- NO selection
- LARGE population
- Mating at RANDOM
- NO migration
Equation to predict ALLELE FREQUENCY:
P + Q = 1
Equation to predict GENOTYPE frequency?
p2 + 2pq + q2 = 1
What is allele frequency affected by?
Dhanya (Differential)
Ruined (Reproductive)
Stephen (Success)
i.e. allele ⬆️ their chance of survival
The two different types of Selection:
- DIRECTIONAL selection 🏃
* STABILISING selection 🚶
When does STABILISING selection 🚶occur?
individuals with ALLELES for CHARACTERISTICS to the MIDDLE of the RANGE are more likely to
• survive and reproduce 👶
- occurs when environment 🌍 IS NOT changing
- reduces the range of possible PHENOTYPES
When does DIRECTIONAL selection 🏃 occur?
individuals with ALLELES for CHARACTERISTICS of an ❌treme TYPE are more likely to
• survive and reproduce
• in response to an ENVIRONMENTAL CHANGE 🌏
Explain how Speciation occurs (6 marks):
- Geographical isolation 🌍
- NO interbreeding between populations 👶
- Variation due to mutation
- DIFF. selection pressures
- DIFF. REPRODUCTIVE SUCCESS
- leads to change in ALLELE FREQUENCY
- Occurs over a LONG PERIOD OF TIME
Define “Dominant” allele:
is ALWAYS e✖️pressed in the PHENOTYPE
Define “Recessive” allele:
- Only expressed in the PHENOTYPE when TWO alleles are present
- is NOT expressed when HETERozygous
