Chapter 5 - The Cell Cycle Flashcards
Give two ways in which the structure of a molecule of tRNA differs from the structure of a molecule of mRNA
- tRNA has standard length
- tRNA has amino acid binding site
- tRNA has hydrogen bonds between base pairs
Explain what is meant by an allele
Different form of a gene
Explain why DNA helicase is important in dna replication
Breaks hydrogen bonds so nucleotides can attach
Explain why the replication of DNA is described as semi conservative
One original strand is conserved. One new complementary strand is made, using the old strand as a template for replication
What is DNA polymerase?
The enzyme that joins free nucleotides to form a new DNA strand
What is DNA helicase?
The enzyme that seperates the DNA double helix by breaking its hydrogen bonds
What is a template strand?
A DNA strand that is being used as a pattern for the assembly of complementary bases into a new strand
What is cytokinesis?
Division of the cytoplasm to give two new cells
What is a centromere?
The structure in a chromosome that holds together chromatids until they are seperated by the spindle fibres
Describe the stage of interphase
Cell makes a copy of its chromosomes involving replication of dna. Cell grows and undergoes its normal physiological functions
Describe the stage of prophase
Chromosomes coil becoming shorter amd fatter. Nuclear envolope disappears. Protein fibres form a spindle in the cell
Describe the stage of metaphase
One or more spindle fibres attaches to centromere of each chromosome. Chromosomes line up in the middle of the spindle.
Describe what happens in the stage of anaphase
Spindle fibres shorten and pull ome of each pair of sister chromatids to opposite poles of the spindle
Describe the stage of telophase
The seperated chromosomes collect at opposite ends of the cell. A new nuclear envelope forms around each set of chromosomes. Cytokinesis occurs
What is binary fission?
The method of cell division found in prokaryotes
