3b - Inheritance Flashcards
What is a gene ?
A section of DNA which codes for one protein
What are the four bases
Adenine
cytosine
guanine
thymine 
How many chromosomes do humans have in each nucleus?
46
Order cell Chromosome gene and nucleus from smallest to largest
Gene, Chromosome, nucleus, cell
How does DNA replicate?
- the double helix strand is split in half
- free nucleotides bond with the opposite bases
- a new DNA complimentary strand is created
What kind of process is DNA replication?
Semiconservative process
What is a protein?
Polymer of amino acids linked by peptide bonds
Where is protein created?
Ribosomes
What are proteins needed for?
- Enzymes
- cell and tissue growth + repair
In RNA what is the sugar?
Ribose
In DNA what is the sugar?
Deoxyribose
Describe RNA
- single stranded
- small
- adenine pairs with URACIL
- sugar is ribose
Describe transcription
RNA binds to DNA strand and travels along, building an mRNA molecule from the template strand
What happens once transcription is complete
mRNA passes into the cytoplasm where it undergoes translation
Describe translation
- mRNA is read to produce a protein chain
- transfer RNA (tRNA) carries specific individual amino acids into the ribosome
What does each tRNA molecule have
Three bases which match up to corresponding bases on the mRNA
What are mutations
Rare random events that change the DNA sequence
How can mutations have a positive effect
By increasing the chance of successful reproduction and survival
How can mutations have a negative effect
By decreasing the chance of successful reproduction and survival
How can mutations be caused
- mistakes in copying DNA
- the effects of radiation
What is the XX chromosome?
Female
What is the XY chromosome?
Male
What is an allele?
Different versions of a gene
What is the definition of heterozygous?
When the 2 alleles of a gene are different
What is the definition of homozygous?
When the 2 alleles of a gene are the same
What is the definition of phenotype ?
The observable characteristics of an organism
What is the definition of genotype?
The combination of alleles which control each characteristic
Who is responsible for determining the sex of offspring and why?
The father because only he can pass on a Y chromosome
What is mitosis ?
Cell devision which forms two identical cells
What is meiosis?
Cell devision which forms 4 non identical haploid cells
What are the uses of mitosis?
- Asexual reproduction
- growth
- repair
Where does meiosis happen in Humans?
Reproductive organs only
What is the definition of codominance?
When both alleles within a genotype are expressed in the phenotype of an individual
What are family pedigrees used for?
To trace the pattern of inheritance of a characteristic through generations of a family
What is monohybrid inheritance?
The inheritance of characteristics controlled by a single gene
What is monohybrid inheritance determined by?
A punnet square
Why is meiosis important?
- increases genetic variation of offspring
What are the different kinds of variation within a species?
Genetic, environmental or both
