Topic 3 - Genetics Flashcards
What does sexual reproduction produce?
Genetically different cells
What type of cell is a gamete?
Haploid cell
What are the two gametes?
- Sperm
- Egg
By what process are gametes produced?
Meiosis
Briefly describe the process of meiosis:
- DNA duplicates
- One chromosome from each parent pairs with another
- Cells divide
- Chromosomes line up again
- Cells divide, forming 4 haploid daughter cells
What type of cell division happens in asexual reproduction?
Mitosis
What are the advantages of sexual reproduction?
- Genetic variation
- Natural selection
What are the disadvantages of sexual reproduction?
- Takes more time and energy
- Two parents needed
What are the advantages of asexual reproduction?
- Produces lots of offspring very quickly
- Only one parent is needed
What are the disadvantages of asexual reproduction?
- No genetic reproduction
- High chance of carrying diseases
What is a DNA strand?
A polymer made up of lots of repeating units called nucleotides
What are the 4 DNA bases?
- Adenine
- Thymine
- Cytosine
- Guanine
What is DNA stored as?
Chromosomes
What is the name given to a section of a chromosome that codes for a protein?
Gene
How are proteins made?
By reading the code in DNA
What is a protein made up of?
A string of amino acids, in a specific order that can fold up into a particular shape
What is a non-coding region of DNA?
An area of the DNA that doesn’t code for an amino acid
What is a genetic mutation?
When part of a gene changes, meaning that the protein cannot fold up, or the amino acids are in the wrong order
Describe transcription in protein synthesis:
- RNA Polymerase binds to the non-coding region of a gene
- The two DNA strands unzip, and the RNA polymerase moves along the strand
- It makes mRNA by using the strand as a template
- Once made, the mRNA moves out and goes to a ribosome
Describe translation in protein synthesis:
- Amino acids are brought to the ribosome by tRNA
- The mRNA shows the order for the proteins to be fitted together in
- Amino acids are joined together in the correct order, forming a polypeptide/protein
What did Mendel do with pea plants?
- Bred a tall and short pea plant, which produced all tall offspring
- Bred these offspring together, and some were tall, so were short
What did Mendel’s experiments show?
The height characteristic was determined by separately inherited ‘hereditary units’ (Tt)
What are alleles?
Different variations of the same gene
What are the two types of allele?
- Dominant
- Recessive
What is a phenotype?
Physical characteristic
What is a genotype?
Combination of alleles
What are the three ways to show inheritance?
- Genetic diagram
- Punnett square
- Family Pedigree
What is the notation in a family pedigree diagram?
- Cricle = Female
- Square = Male
- Coloured = Affected
- Half-Coloured = Carrier
- Empty = Unaffected
What is a sex-linked genetic disorder?
A disorder caused by a faulty allele on a sex chromosome
Name 2 sex-linked genetic disorders:
- Colour blindness
- Haemophilia
Why are males more likely to inherit a sex-linked disorder?
Because they only have 1 X chromosome, so cannot compensate for it as the Y chromosome is a lot shorter
What are the 4 blood groups
- A
- B
- AB
- O
Which two alleles for blood group are co-dominant?
A and B
What is variation?
Differences between organisms of the same species
What was the human genome project?
A project to map every single human gene
How many human genes did the Human Genome project map?
20,500
How long did the Human Genome Project last?
13 years - 1990 until 2013
What are the medical applications for the HGP?
- Prediction of diseases
- Prevention of diseases
- Development of medicines
- Testing for gentic disorders
