Flashcards in Cell Division Deck (43)
What is an Exon?
Regions od DNA that code for proteins
What are the regions between Exons called?
Introns = Non-coding DNA called introns (interruptions)
What are introns?
They contain repeated blocks of nucleotides
What is the function of introns?
The number of times these blocks are repeated produces the genetic variation we see in finger prints.
Do Eukaryotic genes have introns? What does this mean if reference to the type of gene they have?
Yes they have introns which creates discontinuous genes
Do Prokaryotic genes have introns? What does this mean if reference to the type of gene they have?
No they do not have introns which means that have continuous genes
What are the three steps to DNA splicing?
1. A gene composed of exons and introns is transcribed to RNA by RNA polymerase.
2. Processing involves ribozymes and proteins in the nucleus to remove the intron-derived RNA and splice together the Exon- derived RNA into mRNA.
3. After further modification the mRNA travels to the cytoplasm, where is directs protein synthesis.
What is the function of the nucleus?
The nucleus contains the DNA, which carries instructions for the cell-metabolism, enzymes etc.
What is the function of the nucleolus?
Copies instructions from DNA into mRNA. Ribosomes manufacture
What is the function of ribosomes?
They are either attached to the endoplasmic reticulum or free in the cytoplasm. Decodes the instruction contained in the mRNA
What is the function of the Rough Endoplasmic Reticulum?
Protein synthesis on RER and transport of newly made proteins through the cell
What is the function of the Golgi body?
Process and package proteins
What is the function of vesicles?
Transport materials from the ER to the Golgi body to the cell surface membrane or other sites in the cell.
What is the cell in for the majority of the cell cycle?
What occurs during interphase G1?
Protein synthesis, cytoplasm and the number of organelles increase rapidly, mitochondria and chloroplasts also replicate
What occurs during the synthesis phase of mitosis?
DNA replicates (amount of DNA doubles)
What occurs during the G2 phase of mitosis?
The proteins necessary for cell division are synthesised, ATP synthesis increases
What happens during the INTERPHASE phase of a cell?
.DNA replication occurs
.The cell grows in size
.Carries out normal cell activities
.Replicates mitochondria and chloroplasts
Division of one nuclei into two genetically identical ones
What type of division in mitosis?
What is the product of mitosis?
Two genetically identical daughter nuclei, each containing the same number of chromosomes
When is mitosis used? (4)
3.repair of damaged tissue
4.cell replacement of old or damaged cells
Where does mitosis occur?
In all the somatic body cells
What are the four stages of mitosis?
What occurs to the DNA during PROPHASE of mitosis?
.DNA has already replicated
.Chromatin condenses (shortens and thickens) and becomes visible as long threads called chromosomes.
.Each chromosome is made of two genetically identical chromatids held together by a centromere.
What happens during PROPHASE of mitosis after the chromatin has condensed?
.The centrioles move to opposite sides of the nucleus
.The centrioles develop the spindle apparatus
What happens to the nucleolus and nuclear membrane during PROPHASE of mitosis?
.Nucleolus breaks down and disappears
.The nuclear membrane begins to break down
What happens during the METAPHASE of mitosis?
.The nuclear membrane has disappeared
.The microtubules attach to the centromere and cause the chromosomes to arrange on the equator of the spindle
What happens during the ANAPHASE of mitosis?
.The attached microtubules contract which splits the centromeres in two and pulls chromatids to opposite poles of the cell
.Chromatids are now called daughter chromosomes