Explain DNA controlling transport through membrane carrier proteins
Coding information produces a membrane carrier, which contributes to a specified transport route. Gene detection, protein presence and net transport rate are different evidence categories.
Extended only (Supplement); Biology 0610, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked
Before you begin
- Recall the nucleus, DNA base pairing, gametes, fertilisation, enzymes, membrane carriers and chemical synapses.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which chain explains this DNA control example?
What you will learn
- Connect a coding gene with a membrane transport protein
- Distinguish carrier presence from net transport evidence
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Information | Carrier-coding gene |
| Product | Membrane carrier protein |
| Function | Specified substance route |
| Conditions | Protein location, substrate and stated driving conditions |
Connect a coding gene with a membrane transport protein
Membrane carriers are a second required protein example in DNA control of cell function. Gene information is used to make the carrier protein, which contributes to movement of a specified substance across a membrane. The gene does not itself form the working membrane carrier, and a carrier is not simply an empty hole with no molecular specificity.
A carrier protein has a shape that permits interaction with its transported substance under the relevant mechanism. This links ordered protein production with transport function. Some carrier-mediated processes require energy, such as the active-transport models studied earlier, while other facilitated processes differ. Do not state that every carrier always moves every substance using an identical energy rule.
Distinguish carrier presence from net transport evidence
An original model stipulates carrier C transports substance T only when C, T and its required energy condition are present. If C is absent, that particular C-mediated route is unavailable. If another route is explicitly supplied, the conclusion must retain it; absence of one carrier does not automatically prove all membrane movement has stopped.
A record of a carrier gene present in DNA is not a measurement of carrier proteins at the membrane or net transport rate. Production, location, available substance and the stated driving conditions matter. The original diagram shows information, protein and one specified route as separate parts, encouraging an explanation that uses the supplied mechanism rather than a universal transport claim.
Pause and explain
What must accompany a model claim about carrier C transport?
Worked example
A model lacks carrier C but supplies a separate route D. Does all movement stop?
Show the worked solution
- Identify the unavailable C-mediated route.
- Retain the separately stated route D.
Answer The C-mediated route is unavailable, but the record does not establish that separate route D or all movement has stopped.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Explain how DNA can control a specified membrane transport process through a carrier.
Give me a hint
Use the information-to-protein-to-function chain.
Compare my reasoning
- Identify coding information producing the carrier.
- Connect carrier function with the stated substance route.
DNA information is used to produce a membrane carrier protein, which enables its specified substance-transport route under the required conditions.
Look for these in your work
- Name protein production
- Connect the route
In the stipulated C/T model, carrier C is present but required energy is absent. Does presence alone establish C-mediated transport?
Give me a hint
Respect the condition built into this particular model.
Compare my reasoning
- Retain the required-energy condition.
- Reject carrier presence as sufficient proof.
No. This model requires energy as well as C and T; carrier presence alone does not establish the specified transport.
Look for these in your work
- Use the stipulated mechanism
- Reject sufficiency of presence
A carrier gene is detected but membrane protein amount and net movement are not measured. State what cannot be concluded.
Give me a hint
DNA presence is not a membrane-function measurement.
Compare my reasoning
- Separate gene from protein presence and location.
- Separate both from a net transport rate.
The record does not establish membrane carrier amount or a net transport rate; gene detection alone is not those measurements.
Look for these in your work
- Separate presence and location
- State the transport evidence limit
Common mistakes
- A gene is not the working carrier protein.
- Loss of one route does not establish loss of every route.
What can you explain now?
What must accompany a model claim about carrier C transport?
Compare with the explanation
The stated protein substance and driving conditions
Function depends on the supplied mechanism.
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Make it stick
Explain connect a coding gene with a membrane transport protein and distinguish carrier presence from net transport evidence. Use the stated cell, chromosome sets and information pathway before opening the solutions.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.