Genetics and DNA Flashcards
(19 cards)
What is the function of dna
DNA is a set of chemical instructions or “genetic blueprint” needed for a cell to function, grow, reproduce and survive. Controls all cellular activities. It determines inherited characteristics by providing the codes for the body to make specific proteins (protein synthesis)
What is dna made up of?
DNA is a polymer molecule made up of repeating units, or monomers, known as nucleotides. A nucleotide is made up of a phosphate group, deoxyribose sugar and 1 of 4 nitrogenous bases.
Eukaryotes vs prokaryotes?
Eukaryotes: have membrane bound structures inside including a nucleus
Prokaryotes: don’t contain membrane bound organelles and don’t have a nucleus.
What is the purpose of meiosis?
Meiosis occurs in sexually reproducing organisms, involves the production of gametes, or sperm and egg cells, which are haploid cells. Converts diploid cells into haploid daughter cells, reducing the chromosome number by half to ensure offspring have the correct chromosome number.
What is the purpose of mitosis?
Occurs in body cells, for cell regeneration, growth and asexual reproduction. Involves a cell duplicating its chromosomes and separating them to form 2 nuclei, creating 2 diploid daughter cells that are identical to the parent cell.
How does dna replicate?
DNA strands unwind and separate, enzyme dna helicase cleaves apart their hydrogen bonds to create 2 separate strands. DNA polymerase is responsible for assembling the necessary nucleotides to the strands, creating two double stranded identical pieces of DNA.
What is an allele
A variation in a gene. Each individual inherits two alleles, one from each parent
What are sex linked traits
Traits controlled by genes in the sex chromosomes, often found on the X chromosome
What is dna
A polymer molecule made up of repeating monomers called nucleotides. Each nucleotide has three components: phosphate group, deoxyribose sugar and 1 of 4 nitrogenous bases.
What is a mutation
A change in the sequence of dna which can distort the dna structure and make it difficult for the dna to be copied
How is genetic code determined
By the order of the nitrogenous bases, grouped in threes that specify what protein will be made
Why is it important for chromosomes to replicate before cell division occurs.
To ensure the new cells contain the important genetic information the parent cell had
What does recessive mean
An allele that is only expressed if two copies are present.
Why is the network of fibres important in cell division
The fibres extend from the poles of the cell to each chromosome and contract to pull the separated chromatids to opposite poles. This allows for a membrane to enclose the chromosomes at each pole.
What happens in the nucleus between cell divisions
After individual chromosomes become visible the membrane around the nucleus degrades. The separate chromosomes are pulled to the opposite ends of the cell, where a new nuclear membrane encloses them. There are now 2 nuclei with a diploid number of chromosomes which then separates to form 2 diploid daughter cells.
What does autosomal dominant mean?
Only one copy of the abnormal gene from one parent can cause the condition in offspring
What is a trait?
Specific inherited, observable characteristics determined by genetics
Diploid vs haploid cells
Diploid = 2 copies of each chromosome
Haploid = 1 copy of each chromosome
Similarities and differences between meiosis and mitosis
both start with diploid parent cell, both involve dna replication
Mitosis creates 2 diploid daughter cells, whilst meiosis creates 4 haploid daughter cells. More variation and mixing allele combinations in present in meiosis.
