practice questions Flashcards
name the structures when DNA condenses and becomes visible before cell division?
chromosomes
explain the process of transcription and translation:
Transcription: using the information from the DNA, a single strand of
messenger RNA is built. The double-helix is unzipped and then the
complementary strand of mRNA is constructed (with adenine, cytosine,
guanine and uracil instead of thymine). Then, this mRNA leaves the nucleus.
Translation: the mRNA travels to the ribosome (site of protein production).
Every codon (three nucleotides) codes for one amino acid. These amino acids
are carried by a transport RNA molecule and are bonded together and form a protein.
state how many chromosomes you would expect to find in a; a) human somatic cell, b) human gamete;
a=46
b=23
when cells reproduce themselves, the DNA is replicated, explain why;
DNA needs to replicate so that when the cells undergo cytokinesis they have the same amount of
genetic material as the parent cell.
A cell needs to replicate in order for an organism to grow. State the process that will happen, and
outline what occurs at each stage.
The cell will undergo mitosis.
Prophase: the DNA has replicated during interphase. It will condense (fold)
into chromosomes and the nuclear membrane breaks down.
Metaphase: the spindle fibres attach to the centromeres of each chromosome
and pull to align the chromosomes down the centre of the cell.
Anaphase: the spindle fibres contact, pulling one chromatid to each end of the
cell.
Telophase: the nuclear membrane reforms, cell membrane starts to pinch.
The cytoplasm will divide and cell membrane reform during cytokinesis.
What’s the difference between DNA and RNA?
DNA is double-stranded whereas RNA is single-stranded.
DNA has the base thymine whereas RNA has the base uracil.
DNA has deoxyribose sugar whereas RNA has ribose sugar.
state and briefly explain the different types of point mutations;
Insertion- a base is added
Deletion- a base is deleted
Substitution- a base is replaced with another
