8.4 transcription

Dna

Contains dugar deoxyribose

Has bases a, g, c, and t

Typically double stranded

Rna

Contains sugar ribose, which has an additional oxygen atom

Has basers a, c, g, and u

Single strand of nucleotides

What enzyme helps a cell to make a strand of rna

Rna polymerases

First step of transcription

Rna polymerase recognizes the transcription start site of a gene and a large transcription complex of rna polymerases and other proteins assembles on the dna strand and begin to unwind a segment of the dna molecule until two strands separate from each other

Second step of transcription

Rna polymerase string together a complementary strand of rna nucleotides anda dna helix zips back together

Final step of transcription

Rna strand detaches from the dna

MRNA

An intermediate message that is translated teo form a protein

RRNA

Forms part of ribosomes a cell’s protein factories

tRNA

Brings amino acids from the cytoplasm to a ribosome to help make the growing protein

Two ways transcription and replication are similar

Both use a dna template strand to build a new strand

Both use polymerases that add nucleotides

Two ways end results of transcription and replication differ

Replication copies entire genome, transcription copies only specific genes

Replication happens in dna and transcription happens in rna

Replication uses thymine and transcription uses uracil

Replication poduces single stranded RNA and transcription produces double stranded dna

Transcription

Process of copying a sequence of dna to produce a complementary strand of dna

Order of central dogma

Replication (nucleus), dna, transcription (nucleus), rna, translation(cytoplasm)

Start site

Large transcription complex consisting of rna polymerase and other proteins assembles on the dna strnd and begins to unwind a segment of the dna molecule

Transcription complex

Made of rna polymerase and other proteins

Recognizes the start of a gene and begins to unwind the segment of dna

What is stated in central dogma

Information flows in one direction, from dna to rna to proteins