Science 1.2

Whats a double helix composed offrecap

• Double helic composed of two strands of DNA , each with sugar phosphate backbone .

Nitrogenoues base what is that

a nitrogen-containing organic molecule that acts as a fundamental building block of DNA and RNA, forming the "rungs" of the genetic ladder

these bases are adenine , thymine , cytosine , guanine

whats complementary base

Its the base pair of the nitrogenous bases

adenine- thymine and guanine-cytosine

Nucleotide , what is it and what does it consist of ( 3 things)

• Nucleotides consist of sugar molecule , phosphate molecule  and single nitrogenous base .

• This order allow nucleotides on DNA to form specific genes that code for many protein

The nucleotides pair the nitrogenous bases (A,T,G,C) and pairs with its correct complementary base

Whats RNA

ibonucleic acid(RNA) ( Nucleic acid similar to DNA help produce protein from gene of dna )

• Contain nitrgenous bases

• RNA is single strand

• Helps DNA replicate and use genetic information in DNA to produce protein

 

DNA is held by chemical bonds- what is sugar phosphate backbone holding

• Sugar- phosphate backbone is held together by covalent bonds (Phosphodiester bond).

 

• Covalent bonds are strong and hold nucleotides together during replication and protein synthesis.

NOw what are weak bonds point to where it is

Weak bonds

Bons between n itrogenous bases in middle of ladder are weak

• Weak bonds in DNA, primarily hydrogen bonds, are noncovalent interactions between the nitrogenous bases that hold the two strands of the double helix together.

• bonds are weak individually, allowing the DNA to unzip easily for replication and transcription so nucleotides can be read

DNA replication , what are enzyme

• Protein that speeds up chemical reaction and does not get used up

• Molecular machinery

• Usually ends “ase”

Example from text: Dna helllicase,amylase

WHats DNA replication and its process name the first two

 

1. chromosome containing the DNA ‘unwinds’, sothe DNA is in long strands

2. A section of DNA is “unzip” by an DNA helicase (an enzyme), so that the nucleotides on both sides are available

After the nucleotides are avaliable , whats the last two steps

1. New nucleotides are matched to the existing ones on both sides of the DNA via the Complementary  BasePairing Rule by the enzyme DNA polymerase

2. Each new strand is ‘glued’ back together, making two identical double helices from the existing one. These are called daughter molecules.

draw the process of dna replication

after dna replication , what do the two new strands become

Two new strands of DNA compress into chromosomes., and when the cell divides, the two new cells receive identical copy of the replicated DNA. this allows genetic code is passed onto all new cells

State that DNA Replication is semi conservative , what does that mean

each new DNA molecule consists of one original template strand and one newly synthesised strand.

New section , Genes on DNA are use to produce proteins What is the role of DNA when cells do not need to replicate? ( protein synthesis) . name the two steps iof protein synthesis

Protein synthesis

 

Dna contains genes that code for protein

They code through protein synthesis in two steps

1. Transcirption 2. translation

Transcription , is this the begining of protein synthesis and where doe sit occur

Process of producing mrna from dna template

it occurs in the nucleus

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The mrna read unwound section of nucleotide and copies nitrogenous bases that make up gene(e.g A-T turns to A-U) This called complentary strans cause each base is read , the RNA adds opposite , matchin base to chain ( Uracil+adenine Guanine + cytosine)

whats translation second step and where

Translation second step

• Translation is the process where ribosomes in the cytoplasm decode mRNA—produced during transcription—to assemble amino acids into a polypeptide chain, forming a functional protein

• Dna information to codon through MRna

• The ribosome reads the mRNA sequence in sets of three bases called codons.

• Each codon specifies a particular amino acid.

• Amino acids bond together, forming a long chain called a polypeptide.

• This chain folds into functional protein.

What do proteins do

• Cellular processes – usually enzymes, speed up chemical reactions

 

• e.g. amylase breaks down starches when we eat food

 

• Lactase breaks down lactose (sugar in milk)

 

Where does protein help growth

• Muscles are mainly made up of protein

• Heal during injury 

• Reproduction – allows humans to produce hormones such as oestrogen and progesterone