DNA and Its Replication Flashcards
Where are chromosomes found?
Nucleus
What are the packages of information called that chromosomes have?
Genes
What are chromosomes made from?
A chemical called DNA (deoxyribonucleic acid)
What is the DNA wrapped around?
Proteins which allow it to cool up tightly to form chromosomes
What is important to us about DNA?
It is unique to us, it it the chemical code that tells us who we are
- DNA is the core that tells the cell what proteins to make
- we are different depending on what kind of proteins are inside our cells
What is the structure of DNA like?
- double stranded helix
- two single strands wound around each other
- shape called a double helix
What does RNA stand for?
Ribonucleic acid
What kind of bonds are amino acids held together by?
Peptide bonds
What is the genotype determined by?
The sequence of DNA bases
What is a nucleotide?
A molecule of DNA consists of two strands each composed of repeating units called nucleotides. Each DNA nucleotide consists of a molecule of deoxyribose sugar joined to a phosphate group and an organic base.
The arrangement of the two strand with their sugar- phosphate backbones running in opposite directions is described as?
Anti parallel
What is DNA replication described as?
At some point, cells will copy their DNA replication for cell division. This is DNA replication
What happens at the first stage of DNA replication?
The DNA will unwind
What happens at the second stage of DNA replication?
It will begin to unzip
Bright red order of DNA replication? ( learn of by heart)
- The DNA molecule unwinds
- Hydrogen bonds break, ‘unzipping’ the molecule and exposing the bases of both the DNA strand
- A primer attached to one end of each exposed DNA template strand.
- This initiates DNA polymerase to add free complementary DNA nucleotides to the 3’ end of the growing strand
- Hydrogen bonds form between the bases
- Strong chemical bonds from between the phosphate and deoxyribose sugar of adjacent nucleotides.
- Lives enzymes join the fragments to form a complete strand
- Each replicated DNA molecule is made of one original template strand and a newly synthesised strand.
What are the four types of nucleotides?
- adenine
- thymine
- cytosine
- guanine
Why does each strand have a 3’ or a 5’?
Determined by whether the third or the fifth carbon on the sugar molecule of the nucleotide is closest to the end.
Why must DNA replicate?
Before cell division can occur, ensuring daughter (new) cells have a complete set of genetic information.
Difference between mitosis and meiosis?
Mitosis- is the type of division that replaces diploid body cells
Meiosis - is the type that produces haploid gametes
What does it mean when the DNA unwinds?
The ‘double helix’ shape is lost
What does it mean when the DNA unzips?
The hydrogen bonds between the bases break, separating the two strands
What must be available in the cell for DNA replication to take place?
- Free nucleotides
- ATP (energy)
- DNA polymerase
- A template of DNA
- DNA ligase
Two things to know about DNA polymerase?
- It can only add a nucleotide on to the 3’ end of a new strand
- It can’t start a new strand on its own- it can only add on to an existing strand
What is a ‘primer’? Yeah
A short single stranded piece of DNA, capable of hybridising to its complementary sequence of DNA.
