Ch 10.4 Protein Synthesis - Mrs. Rasmussen Biology

[Pages:17]Ch 10.4 Protein Synthesis

I) Flow of Genetic Information A) DNA is made into RNA which undergoes transcription and translation to be made into a protein.

II) RNA Structure and Function A) RNA contains 4 Nitrogenous bases ? Adenine, Cytosine, Guanine, Uracil B) 3 Types of RNA (Messenger RNA / Ribosomal RNA / Transfer RNA)

Gene expression: The process by

which DNA directs the synthesis of proteins.

The Genetic Code

The DNA molecule, with its four nitrogenous bases, is the code for all

Proteins that are made in a cell.

Genes are made of DNA. A gene is the coded DNA instructions that controls the production of specific Proteins, such as enzymes, structural proteins, oxygen-carrying proteins, etc.

The expression of genes includes two stages: transcription and translation

III) Transcription A) Transcription ? Is the process by which DNA is copied into RNA B) Promoters ? signals in DNA that indicate to the enzyme where to start making RNA C) Terminations Signal ? a specific sequence of nucleotides that stops transcription

Transcription occurs inside the Nucleus

The Code Is A Triplet

1. Proteins are made of building blocks called: amino acids.

2. There are _2_0_ different amino acids and _fo_u_r_ different nucleotides (since there are four different nitrogenous bases).

3. It was discovered that _th_r_e_e_n_u_c_l_e_ot_id_e_s_ in sequence must specify each _a_m_i_n_o_a_c_id__. This would provide for _6_4_ possible combinations of amino acids.

4. Each _t_r_ip_le_t_ of nucleotides is called a __c_o_do_n__.

The Code Is A Triplet

5. Each codon calls for a specific _a_m_i_n_o_a_c_id__. When many _a_m_i_n_o_a_c_id_s_ are linked together a _p_ro_t_e_in_ is made.

6. A few codons do not call for any amino acids. One codon acts as a _"_s_ta_r_t"_ codon to tell where the sequence of amino acids is to begin. Three other codons are _"_st_o_p_"_c_o_d_o_n_s__ and act as signals for the end of a protein chain.

7. A gene on a chromosome is many, many codons long. Each gene is the code for a particular _p_ro_t_e_in_.

8. Genes provide the _i_ns_t_ru_c_t_io_n_s_ for making specific proteins, but a gene does not build a protein directly. The bridge between DNA and protein synthesis is:

DNA vs. RNA

? DNA

? RNA

? Sugar (Deoxyribose) ? Sugar (Ribose)

? Phosphate Group

? Phosphate group

? Nitogenous Bases

? Nitrogenous Bases

?A

?A

?T

?U (Not "T")

?G

?G

?C

?C

? Double Stranded

? Single Stranded

Functions of RNA

1. Proteins are made in the _rib_o_s_o_m_e_s in the cytoplasm.

1. DNA determines which proteins need to be made.

2. A gene on the DNA molecule is _c_o_p_ie_d_. This copy is called _R_N_A_. The copy of the instructions is then sent out to the r_ib_o_s_o_m__e_s_in__th_e__cy_t_o_p_la_s_m__.

3. RNA carries the messages from the DNA (in the nucleus) to the ribosomes (in the cytoplasm). RNA tells the ribosomes which proteins to make and how to make them.

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