The Cell Cycle And Differentiation 2.4 Flashcards
What happens in the interphase stage?
The cell carries out normal functions, but also prepares to divide. The cells DNA is unravelled and replicated, to double it’s genetic content. The organelles are also replicated. It’s ATP content is increased.
Interphase is subdivided into 3 separate growth stages, what are they?
G1: cell grows and new organelles and proteins are made
Synthesis: cell replicates it’s DNA, ready to divide by mitosis
G2: cell keeps growing and proteins needed for cell division are made
What happens in semi-conservative replication?
The enzyme, DNA helicase breaks the hydrogen bonds between the two polynucleotide DNA strands, the helix unzips to form two single strands. Each original strand acts for a new strand a new DNA strand is formed as a pair, this is specific base pairing. The nucleotides are joined together by the enzyme, DNA polymerase and hydrogen bonds form.
What is the cell cycle?
The process of cell growth and division.
What happens in prophase?
The chromosomes condense, getting shorter and fatter. Tiny bundles of protein called centrioles start moving to opposite ends of the cell forming a network of spindle fibres. The nuclear envelope breaks down and chromosomes lie free in the cytoplasm.
What happens during metaphase?
The chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere.
What happens during anaphase?
The centromeres divide, separating each pair of sister chromatids, the spindles contract, pulling chromatids to opposite ends of the cell, centromere first.
What happens during telophase?
The chromatids reach the opposite poles on the spindle. They uncoil and become very long and thin again, they’re now called chromosomes again. A nuclear envelope forms around each group of chromosomes, there are now two nuclei.
What causes uncontrolled cell division and what is the result?
A mutated gene causes uncontrolled cell division.
And tumours, which can become cancerous can happen as a result.
Outline some cancer treatments that act on uncontrolled cell division and how they work.
G1 (cell growth and protein production) some chemical drugs (chemotherapy) prevent the synthesis of enzymes needed for DNA replication. So if the cell is unable to start the phase, the cell is forced to kill itself.
What is the process called where a cell becomes specialised?
Differentiation
What is an organ?
A group of different tissues that work together to perform a particular function,
An example of a plant organ would be…..?
A leaf
