Unit 2- Section 4 The Cell Cycle And Differentiation Flashcards
What happens during the second stage of DNA replication?
each original single strand acts as a template for a new strand. Free-floating DNA nucleotides join to the exposed bases on each original template strand by specific base pairing.
What happens during the first stage of DNA replication?
The enzyme DNA helicase breaks the hydrogen bonds between the two polynucleotide DNA strands. The helix unzips to form two single strands
What happens during the third stage of DNA replication?
The nucleotides on the new strand are joined together by the enzyme DNA polymerase. Hydrogen bonds form between the bases on the original and new strand. Each new DNA molecule contains one strand from the original DNA molecule and one new strand
This type of copying is called semi-conservative replication because half of the new DNA molecules are from the original piece of DNA
What is the cell cycle?
It is the process that all body cells from multicellular organisms use to grow and divide.
When does the cell cycle start and finish?
Starts when a cell has been produced by cell division and ends with the cell dividing to produce two identical cells.
What does the cell cycle consist of?
A period of cell growth, and DNA replication called interphase and. Period of cell division called mitosis. Interphase is subdivided into three separate growth stages
Describe the three stages within interphase
Gap phase 1- cell grows and new organelles and proteins are made
Synthesis- cell replicates it’s DNA ready to divide my mitosis
Gap phase 2- cell keeps growing and proteins are needed for cell divisions are made
What happens during interphase?
The cell carries out normal functions, but also prepares to divide. The cells DNA is unravelled and replicated, to dale it’d genetic content. The organelles are also replicated so it has spare ones,and it’s ATP contain is increased. (ATP provides the energy for cell division)
What happens during mitosis?
There are two types of cell division, mitosis and meiosis. Mitosis is the form of cell division that occurs during the cell cycle. In mitosis a parent cell divides to produce to genetically identical daughter cells.
Why is mitosis needed?
It is needed for the growth of multicellular organisms and for repairing damaged tissues,
What are the stages within mitosis?
Prophase, metaphase, anaphase, telophase
What are the structure of chromosomes in mitosis?
As mitosis begins, the chromosomes are made of two strands joined in the middle by a centromere. The separate strands are called chromatids. Two strands on the same chromosome are called sister chromatids. There are two strands because each chromosome has already made an identical copy of itself during interphase. When mitosis is over the chromatids end up as one strand chromosomes in the new daughter cells
What happens during prophase?
The chromosomes condense, getting shorter and flatter. Tiny bundles of protein called centrioles start moving to opposite ends of the cell, forming a network of protein fibres across it called the spindle, the nuclear envelope breaks down and chromosomes lie free in the cytoplasm
What happens during metaphase (2nd stage)
The chromosomes line up along the middle of the cell and become attached to the spindle by their centromere
What happens during anaphase (3rd stage)
The centromeres divide, separating each pair of sister chromatids. The spindles contract, pulling chromatids to opposite ends of the cell centromere first
