Mechanism of Protein Synthesis

Mechanism of Protein Synthesis

1. Transcription

The process by which an m-RNA copy is made of a portion of DNA is called transcription, which involves the following steps:

(i). Promotor(P)

Start signals from DNA are called promotors(P). Promotors have an ATP rich region some ten bases before mRNA with the common sequence TATATAG. In addition to this region, enzyme also recognises a DNA region located bases before the start of mRNA called I-site (initiation site).

(ii). Binding to the promotors(P) site

RNA polymerase recognises p-site with the help of a protein factor called CAP-factor. The sigma factor of RNA polymerase recognises the CAP-factor and help in opening of DNA duplex at its P-site.

(iii). RNA Chain Initiation and Elongation

Since 5’ end of many RNA has either PPPA or PPPG, either ATP or GTP is probably bound by the enzyme at P-site and becomes the initial 5’ terminal nucleotide residue. The open or melted complex now initiates transcription at I-site (adjacent to the P-site) in presence of nucleoside triphosphate. During elongation, RNA polymerase copies DNA sequence accurately progressing at the speed of 30 nucleotides per second. Elongation of RNA nucleotide only in 5’ to 3’ direction.

(iv). RNA Chain Termination

Termination of RNA moloecule occurs when the energy arrives at the stop signal on DNA. A termination factor, called rho factor, causes the release of the transcribed RNA molcules. The termination signal recognised by RNA polymrase on DNA is a GC rich region. Many RNA polymeras molcules can be working to produce m-RNA trascripts at the same time.

2. Translation

The process by which an m-RNA transcript determines the squnc of amino acids in a polypptide is called translation. It involves the following stps:

(i). Activation of Amino Acid

Amino acid is activated by the reaction with ATP in the presence of specific enzyme aminoacyl synthetase and Mg²⁺ . In this process, amino acid adenylate is formed and pyrophosphate (PP) is released. The amino acid is attached always at CCA end of s-RNA.

(ii). Transfer of Amino to t-RNA

t-RNA reacts with citidine triphosphate (CTP) and ATP before amino acid is transfered to it. AMP and amino-acyl synthetase enzyme ar reeleased.

(iii). Initiation of Polypeptide Syntheesis

In the cytoplasm the ribosome is dissociated into two subunits (30s and 40s subunits in prokaryotes and 40s and 60s subunits in eukaryotes). The 30s subunit attaches at the 5’ nd of m-RNA carrying AUG codon. This attachment is carrid out in th presence of protein factor (F₃). The t-RNA carrying methionine t-met RNA binds with 30s m-RNA complex. At this stage 50s of prokaryotic ribosome associates with 30s subunit and forms 70s ribosome in presence of protein factor(F₂).

(iv). Elongation and termination of Polypeptide Chain

Elongation of polypeptide chain involves the following 3-steps-

Binding of AA-tRNA (amonoacyl complex) at the A-site of ribosome.

Formation of polypeptide chain.

Translocation of peptide-t RNA from A- site.

Termination of polypeptide chain involves the following events

Polypeptide chain is released by the hydrolytic splitting of the last polypeptide t-RNA ester linkage and ribosome is dissociated from m-RNA.

Termination is brought about by UAA, UAG and UGA (nonsense codons).

Models	Key person/s	Focus	View on behavior	View on client	Role of counselor	techniques
Psychoanalytic theory	Sigmund Freud	To reduce tension; Unconscious factors that motivate behavior	Human behavior is directed toward reduction of his tension	Weak and uncertain and in need of assistance in reconstructing a normal personality.	The expert who will facilitate or direct this restructuring	Projective tests, play therapy, dream analysis, and free association, all of which require special training
A theory of personality development, a philosophy of human nature, a method of psychotherapy. Attention is given to the events of the first 6 yrs of life as determinants of the later development of personality. Usually used for abnormal behavior. Defense mechanisms: repression, rationalization, regression, identification, displacement(e.g. sublimation), overcompensation (reaction formation)
Individual Psychology	Alfred Adler Rudolf Dreikurs	On the uniqueness of individuals	There exist within the human being an innate drive to overcome perceived inferiorities and to develop one’s own potential for actualization	Sees the person holistically	Therapist and counselee works together to help the counselee develop awareness	· Analysis and assessment · Exploration of family constellation · Reporting of earliest recollection · Confrontation · Cognitive restructuring · Challenging of one’s belief system · Exploration of one’s social dynamics and of one’s unique style of life
A growth model It stresses taking responsibility, creating one’s own destiny, and finding meaning and goals to give life direction. Sources of inferiority: biological dependency, our image of ourselves in relationship to the grandeur of the universe, organ inferiority. Four stages: Establishing relationship (through a subjective/objective interview. Client is helped to feel comfortable and is encouraged to explain what specifically has helped him/her the need for counseling). Diagnostic stage (lifestyle interview). Interpretation (the time during which the counselor and the client develop insight from the client’s basic mistakes by analyzing and discussing the convictions, goals, and movement in the client developed early in life and the ensuing thought, emotional, and behavioral, patterns and attitudes). Reorientation (the therapist helps the counselee to move from intellectual insight to actual development and expression or healthier attitudes and behaviors).
Models	Key person/s	Focus	View on behavior	View on client	Role of counselor	techniques
Person-centered self-theory	Carl R. Rogers		The better clients know themselves, the more likely they are to identify the most appropriate behavior for themselves	Basically good and possessing the capabilities for self understanding, insight, problem solving, decision making, change and growth.	Facilitator and reflector	To provide a climate in which the counselee could bring about change in him.
A non-directive reaction against psychoanalysis Based on the subjective view of human-experiencing, it places faith in and gives responsibility to the client in dealing with problems
Behavioral theory	John B. Watson, B.F. Skinner, Albert Bandura, Arnold Lazaruz	On specific behavioral goals, emphasizing precise and repeatable methods.	A set of learned responses of events, experiences or stimuli in a person’s life history.	People have the capacity to act in either rational or irrational manner What a person tells himself is intimately related to the way that person feels or acts.	Teacher or coach	Reflection Summarization Open-ended inquiries
Applies the principles of learning to the resolution of specific behavioral disorders.
Rational emotive behavior therapy (cognitive behavior)	Albert Ellis	Reduce or eliminate irrational behavior	People have the capacity to act either rational (effective and potentially productive) or irrational manner (results in unhappiness and nonproductivity).	What a person tells himself is intimately related to the way that person feels or acts.	Teacher-student	Teaching (e.g. reading) Questioning and challenging Confrontation tactics Contracts Suggestions persuasion
Action-oriented, highly dictative, cognitive model of therapy Role of significant others (environment, culture)

Models

Key person/s

Focus

View on behavior

View on client

Role of counselor

techniques

Reality choice therapy	William Glasser	Focuses on present behavior and does not emphasize the clients past history	Based on the premise that a single psychological need is present throughout life: the need for identity	Client will assume personal responsibility for his or her well-being
A short term approach focusing on the present, it stresses a person’s strengths; clients learn more realistic behavior and thus achieve success. Counseling is simply a special kind of training that attempts to teach an individual what he or she should have learned during normal growth in a rather short period of time. Components of total behavior: 1. active behavior 2. thinking 3. feeling 4. physiology as the capacity to produce voluntary and involuntary body mechanisms Four needs of humans: need to belong need for power need for freedom need for fun and recreation
Existential therapy	Victor Frankl Rollo May Irvin Yalom	Quality of person-to-person therapeutic relationship	Individuals define who they are by their choices even though there may be factors beyond one’s control that restricts ones choices.	Client has free-choice; has a purpose in life	Improves clients relationship with others
Stresses building therapy on the conditions of human existence (choice, freedom and responsibility, self determination. For the individual to find meaning in one’s life through self awareness Models Key person/s Focus View on behavior View on client Role of counselor techniques
Transactional analysis	Eric Borne		Normal personality is a product of healthy parenting		Seek to restore damaged ego and to develop the client’s capacity to use all ego states appropriately
Gestalt counseling	Frederick Perls Fritz and Laura Perls		Only the present is important	Has the capacity for self-direction	Assist the client toward self-integration Seeks to increase the client’s self-awareness
An experimental therapy stressing awareness and integration. It grew as a reaction against analytic therapy Integrates function of body and mind Models Key person/s Focus View on behavior View on client Role of counselor techniques
Family systems therapy				That the client cannot be completely understood apart from his/her family	Assist families
Multi-modal theory	Arnold Lazarus			Are more frequently troubled by a multitude of problems that can be more efficiently dealt with by using a broad range of special methods	use unique assessment procedures

Models of counseling

Models of counseling	Description	Counselors view about the individual/ client	Techniques/ skills used
Psychoanalytic theory	· Its focus is on unconscious factors that motivate behavior · A theory of personality development, a philosophy of human nature, a method of psychotherapy. · Attention is given to the events of the first 6 yrs of life as determinants of the later development of personality. · Usually used for abnormal behavior.	Weak and uncertain and in need of assistance in reconstructing a normal personality.	· Projective tests, · play therapy, · dream analysis, and · free association, all of which require special training
Individual Psychology	· Focuses on the uniqueness of individuals · There exist within the human being an innate drive to overcome perceived inferiorities and to develop one’s own potential for actualization	Sees the person holistically	· Analysis and assessment · Exploration of family constellation · Reporting of earliest recollection · Confrontation · Cognitive restructuring · Challenging of one’s belief system · Exploration of one’s social dynamics and of one’s unique style of life
Person-centered self-theory	· A non-directive reaction against psychoanalysis · Based on the subjective view of human-experiencing, it places faith in and gives responsibility to the client in dealing with problems	Clients are basically good and possessing the capabilities for self understanding, insight, problem solving, decision making, change and growth.	· Provide a climate in which the counselee could bring about change in him.
Behavioral theory	· It focus is on specific behavioral goals, emphasizing precise and repeatable methods. · Sees behavior as a set of learned responses of events, experiences or stimuli in a person’s life history. · Applies the principles of learning to the resolution of specific behavioral disorders.	People have the capacity to act in either rational or irrational manner What a person tells himself is intimately related to the way that person feels or acts.	· Reflection · Summarization · Open-ended inquiries
Rational emotive behavior therapy (cognitive behavior)	· Action-oriented, highly dictative, cognitive model of therapy · Role of significant others (environment, culture) · The goal is to reduce or eliminate irrational behavior	Sees the clients as a person who has the capacity to act either rational (effective and potentially productive) or irrational manner (results in unhappiness and non-productivity). What a person tells himself is intimately related to the way that person feels or acts.	· Teaching (e.g. reading) · Questioning and challenging · Confrontation tactics · Contracts · Suggestions · persuasion
Reality choice therapy	· Focuses on present behavior and does not emphasize the clients past history · Based on the premise that a single psychological need is present throughout life: the need for identity · A short term approach focusing on the present, it stresses a person’s strengths; clients learn more realistic behavior and thus achieve success. · Counseling is simply a special kind of training that attempts to teach an individual what he or she should have learned during normal growth in a rather short period of time.	Client will assume personal responsibility for his or her well-being	· Involvement · Current behavior and evaluating your behavior · Planning possible behavior · Commitment to the plan · No Excuses, No Punishment, Never Give Up
Existential therapy	· Stresses building therapy on the conditions of human existence (choice, freedom and responsibility, self determination. · For the individual to find meaning in one’s life through self awareness · Focuses on the quality of person-to-person therapeutic relationship	Individuals define who they are by their choices even though there may be factors beyond one’s control that restricts ones choices. Client has free-choice; has a purpose in life	· person-to-person therapeutic relationship
Transactional analysis	· Normal personality is a product of healthy parenting · Counselor seeks to restore damaged ego and to develop the client’s capacity to use all ego states appropriately	Assumes a person has the potential for choosing and redirecting or shaping one’s own destiny.	· An essential technique is the contract that precedes each counseling steps. · Sessions are tape recorded in their entirety.
Gestalt counseling	· An experimental therapy stressing awareness and integration. · It grew as a reaction against analytic therapy · Integrates function of body and mind · Only the present is important	Client has the capacity for self-direction so the counselor assist the client toward self-integration and seeks to increase the client’s self-awareness	· How and what questions · confrontations · ‘I’ statements · Sharing awareness with clients emphasizing this moment
Family systems therapy	· Mentally healthy persons have both good family relations and also satisfactory relationships outside the family.	That the client cannot be completely understood apart from his/her family	· Counselors help individuals who need better relationships with important people in their lives in or out of the family unit.
Multi-modal theory	· A systematic and comprehensive approach · Characterized by unique assessment procedures and by significant emphasis on and attention to details of imagery, cognitive, and interpersonal factors and their interactive effects on the client. · This theory is personalized and individualistic.	That the client is more frequently troubled by a multitude of problems that can be more efficiently dealt with by using a broad range of special methods	· Technical eclecticism (the idea that treatment can and should consist of techniques from many different theoretical perspectives, without the clinician necessarily adopting the theoretical basis for those techniques.)