Genetics topic 3 Flashcards
Asexual Reproduction
Advantages:
No need to find a mate.
Rapid reproductive cycle.
Efficient in stable environments.
Disadvantages:
No variation in the population.
Less adaptability to changes in environment.
Sexual Reproduction
Advantages:
Produces genetic variation in offspring.
Increases chances of survival in changing environments.
Disadvantages:
Requires finding a mate.
Slower reproduction process.
Meiosis
Produces four daughter cells.
Each cell has half the number of chromosomes (haploid).
Results in genetically different gametes.
Structure of DNA
DNA is a polymer made up of two strands coiled into a double helix.
Strands are linked by complementary base pairs (A-T, C-G) with hydrogen bonds.
Nucleotides consist of a sugar, phosphate group, and a base (A, T, C, G).
Genome and Gene
Genome: The entire DNA of an organism.
Gene: A section of DNA that codes for a specific protein.
Extracting DNA from Fruit
Steps:
Crush the fruit to break cell walls.
Add detergent to break down cell membranes.
Filter the mixture to remove large particles.
Add alcohol to precipitate DNA.
DNA Bases and Proteins
The order of bases in DNA determines the order of amino acids in a protein.
Proteins fold into specific shapes, like enzymes.
Protein Synthesis (Transcription and Translation)
1 RNA polymerase binds to non-coding DNA in front of a gene.
2 mRNA strand is produced from the coding DNA.
3 mRNA attaches to a ribosome.
4 Codons in mRNA code for specific amino acids.
5 tRNA transfers amino acids to the ribosome.
6 Amino acids link to form a polypeptide.
Genetic Variants and Phenotype
Non-coding DNA variants can affect how much protein is produced.
Coding DNA variants can alter amino acid sequence, changing the protein’s activity.
Alleles and Inherited Characteristics
Inherited characteristics differ due to different alleles of genes.
Dominant alleles mask recessive alleles in heterozygous individuals.
Gregor Mendel and Genetics
Mendel discovered the principles of inheritance by studying pea plants.
His work was not understood until the discovery of DNA.
Key Terms in Genetics
Chromosome: Structure of DNA.
Gene: Section of DNA.
Allele: Variant of a gene.
Dominant/Recessive: Type of allele.
Homozygous/Heterozygous: Identical/different alleles.
Genotype: Genetic makeup.
Phenotype: Physical characteristics.
Gamete: Sex cell (sperm/egg).
Zygote: Fertilized egg.
Monohybrid Inheritance
Use Punnett squares to predict offspring traits.
Show the inheritance of dominant and recessive traits.
Sex Determination
XX = female, XY = male.
Genetic diagrams can show how sex is determined.
Monohybrid Cross Outcomes
Outcomes from monohybrid crosses can be analyzed using probabilities, ratios, and percentages.
Sex-Linked Disorders
Sex-linked genetic disorders are often carried on the X chromosome.
Males are more likely to express these disorders (e.g., hemophilia).
ABO Blood Groups Inheritance
Codominance occurs when both alleles contribute to the phenotype (e.g., blood type AB).
Multiple alleles include A, B, and O blood types.
Causes of Variation
Genetic variation: Due to mutations and sexual reproduction.
Environmental variation: Caused by environmental factors (e.g., diet, climate).
Effects of Mutations on Phenotype
Most mutations have no effect.
Some mutations have small effects, while rare mutations can have significant effects.
Human Genome Project
Mapped the entire human genome.
Applications include personalized medicine and gene therapy.
Genetic Variation
There is usually extensive genetic variation within a species.
Variations arise through mutations.
Estimations
Use estimations to simplify complex calculations in genetics.
Example: Estimating the probability of offspring inheriting a trait.
Numerical and Graphical Forms
Translate information between numerical and graphical forms.
Example: Use a graph to represent the proportion of offspring inheriting a trait from a Punnett square.
Data Extraction from Graphs and Tables
Extract and interpret data from graphs, charts, and tables.
Example: Analyzing inheritance patterns or genetic variation from a data table.
Direct Proportions and Ratios in Genetic Crosses
Use direct proportions and simple ratios in genetic crosses.
Example: In a monohybrid cross, the ratio of offspring traits may be 3:1 for dominant and recessive traits.
Probability in Genetic Crosses
Use the concept of probability to predict outcomes of genetic crosses.
Example: Probability of inheriting a dominant or recessive allele
Calculating Arithmetic Means
Calculate arithmetic means to determine the average outcome from multiple genetic crosses.
Example: Average percentage of offspring displaying a specific trait.
Using Percentages in Genetic Analysis
Calculate percentage gain and loss of a particular genetic trait.
Example: Percentage of offspring with a specific phenotype from a Punnett square.
Using Percentiles
Understand and use percentiles in monitoring growth or genetic traits.
Example: Comparing genetic trait distribution in a population using percentiles.
