Compare two BLAST hits: E-value and query coverage

Open your materials, follow the steps, then turn in your work.

Compare two recorded hits using percent identity, E-value and query coverage, then write a qualified statement that matches the evidence.

1. Open your materials

Use the materials named in the first step below. Open lesson resources.

2. Start the work

Choose two usable hits from your saved Monday record. If unavailable, use the supplied A/B illustrative practice and label that route. Keep the actual missing or unfinished step noted separately in the same record.

Show all 6 required steps

Choose two usable hits from your saved Monday record. If unavailable, use the supplied A/B illustrative practice and label that route. Keep the actual missing or unfinished step noted separately in the same record.
Read the definitions of query, hit, percent identity, query coverage and E-value. Use the notation aid before copying a small E-value.
Fill both rows of the comparison table from the chosen evidence. Keep the source and context with the actual column labels. Do not invent a missing value.
Compare percent identity, query coverage and E-value together. Explain what the recorded measures support. If the measures conflict or information is missing, state the uncertainty instead of forcing a winner.
Revise the statement so it cites all three recorded measures and stays within the claim limit. Keep illustrative practice separate from an actual search result.
Check the two rows, source label and statement. Submit one PDF through assignment 8520302476, unless your paper was collected in class. Keep the record for later work.

Lost your place? Choose your evidence route first: two usable hits from Monday, or supplied A/B skill practice. Then fill both table rows, compare the three measures and revise the same statement. Do not switch to a different task.

Check your work before submitting

Record two hits with all three measures and their source/context.
Explain the comparison using the supplied definitions and a stated limit.
Submit one labeled comparison product without claiming practice is an actual search.

3. Turn in your work

DueSept. 15, 11:59 PM

Hand in: One two-hit comparison table and a revised, qualified statement citing percent identity, E-value and query coverage.

How to submit and name your file

Submit the table and revised statement together as one PDF to Schoology assignment 8520302476 by Tuesday, September 15 at 11:59 PM. If your paper was collected in class, do not upload it again. Keep your original record.

In Schoology, open your course and the assignment for this lesson. Attach your file, select Submit, and check that it appears in the submission.

PDF upload help

You get two school days for every day you were absent, so this deadline moves with you.

Open Schoology I was absent

Find this lesson's Schoology assignments

These are existing assignments for your section. Follow the directions in the assignment you are working on; this list does not add new work. Check Schoology for each deadline.

Wk4 Data table: E-value and query coverage

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How this lesson connects

On Monday, you saved your input source, search settings and actual result or unfinished step. Reopen that record. The tutorial checked the workflow; it did not validate the case identification.

Need help getting started?Help: worked example Missed class?

Need help? Warm-up, timing, and directions▸

💡 Big idea: Read , and E-value together before writing a qualified comparison.

0-10 minReopen Monday's record and choose actual hits or the labeled A/B practice route.
10-25 minRead the five definitions and notation aid. Locate each measure in the supplied example.
25-40 minFill both rows from the same chosen evidence context. Check the recorded values.
40-55 minCompare all three measures. Discuss disagreement or missing information without forcing a winner.
55-70 minRevise the qualified statement using the recorded measures and claim limit.
70-80 minCheck the source label, two rows and statement; submit the same product once and keep the record.

Mr. Mendoza's 5-minute intro

• On Monday, you saved your input source, search settings and actual result or unfinished step. Reopen that record. The tutorial checked the ; it did not validate the case identification.
• One two-hit comparison table and a revised, qualified statement citing , E-value and .
• Use two usable hits from your own saved Monday record. Keep the input source and actual search settings with the table. Copy the recorded values without guessing.
• If your Monday record is unavailable or has fewer than two usable hits, use supplied illustrative hits A and B for the same table and statement. Label your work “Skill practice using supplied illustrative values”. Note your actual missing or unfinished investigation step separately in the same PDF.

Know by the end

• Query: The input sequence being compared with database entries.
• Hit: A database entry returned with an to the query.
• : The percentage of positions in the reported with identical letters. It does not describe unaligned parts of the query.
• : The percentage of the query represented in the or alignments reported for that hit. Keep the actual column label and comparison context.
• E-value: The expected number of alignments with that score or better arising by chance for that database search. It is an expected count, not a probability or percent.
• Smaller E-values indicate greater in the relevant search context. No universal cutoff or disease-identification guarantee follows.
• 2e-60 means 2 × 10^-60. Retain the recorded notation. Do not round a small value to zero or turn it into a diagnostic probability.

PLTW connection and today's work

Original local comparison practice connected to PLTW MI Activity 1.1.3. Official materials remain in the class hub. Completing this practice does not certify official PLTW completion.

Today's stopping point: Complete today's local comparison practice. Do not claim a new search, missing Monday work or the full official activity is complete.

Today uses John Hay teacher-created practice. It builds skills for the course, but does not count as completing an official myPLTW activity.

Course connection

Activity 1.1.3 Using DNA to Identify Pathogens

Use the turn-in directions at the top of this page. Do not create a second submission unless your teacher asks for one.

Show another explanation or a smaller first step

Need help? Choose a starting point

Need a running start

Read these definitions before comparing the rows. Keep each result's actual column label and comparison context. 2e-60 means 2 × 10^-60. Retain the recorded notation. Do not round a small value to zero or turn it into a diagnostic probability.

On track

Use two usable hits from your own saved Monday record. Keep the input source and actual search settings with the table. Copy the recorded values without guessing. One two-hit comparison table and a revised, qualified statement citing percent identity, E-value and query coverage.

Stuck? Get unstuck

If your Monday record is unavailable or has fewer than two usable hits, use supplied illustrative hits A and B for the same table and statement. Label your work “Skill practice using supplied illustrative values”. Note your actual missing or unfinished investigation step separately in the same PDF. This completes the local comparison-practice product only. It does not record a successful search, finish the missing Monday activity or certify official PLTW completion.

Push me further

Optional: explain what remains uncertain in the same comparison. Add no new numerical result or separate submission.

Lesson resources: reading, slides, and vocabulary▸

Socratic teaching slide deck

Use the deck and optional guided notes for the same two-hit table and qualified statement. Submit one PDF or collected paper. No extra exit ticket or group product is due.

Generated from this lesson's canonical data with a red-team citation check.

Open slides on Google Drive Optional guided notes (PDF) Citation audit

Carry forward

On Monday, you saved your input source, search settings and actual result or unfinished step. Reopen that record. The tutorial checked the ; it did not validate the case identification.

Daily take-home

Read , and E-value together before writing a qualified comparison.

Comparison record and practice support

Read these definitions before comparing the rows. Keep each result's actual column label and comparison context.

Query: The input sequence being compared with database entries.
Hit: A database entry returned with an alignment to the query.
Percent identity: The percentage of positions in the reported alignment with identical letters. It does not describe unaligned parts of the query.
Query coverage: The percentage of the query represented in the alignment or alignments reported for that hit. Keep the actual column label and comparison context.
E-value: The expected number of alignments with that score or better arising by chance for that database search. It is an expected count, not a probability or percent.

2e-60 means 2 × 10^-60. Retain the recorded notation. Do not round a small value to zero or turn it into a diagnostic probability.

Choose your evidence route

Use two usable hits from your own saved Monday record. Keep the input source and actual search settings with the table. Copy the recorded values without guessing.

This completes the local comparison-practice product only. It does not record a successful search, finish the missing Monday activity or certify official PLTW completion.

F1. Two-hit comparison record

Hit label	Percent identity	E-value	Query coverage
[first hit]	[recorded value]	[recorded value]	[recorded value]
[second hit]	[recorded value]	[recorded value]	[recorded value]

Evidence route: actual record or skill practice: ____________________
Source and comparison context: ____________________
Actual database/program settings for actual records: ____________________
Missing or unfinished investigation step, if applicable: ____________________

Qualified statement: ____________________

Do not invent actual settings for the illustrative practice.

F1. Blank record layout, not search data. The separate A/B practice is labeled illustrative.

Open supplied A/B practice and a statement model

Illustrative practice values, not a BLAST run or case result.

Assume the same illustrative comparison context for A and B. No sequence, organism or disease is supplied.

Hit label	Percent identity	E-value	Query coverage
A	99%	2e-60	98%
B	99%	0.4	11%

Illustrative practice values, not a BLAST run or case result. In the same illustrative comparison context, A and B both have 99% identity. A has greater query coverage (98% versus 11%) and a smaller E-value (2e-60 versus 0.4), supporting a stronger reported sequence-similarity comparison for A. This does not establish an organism's identity, a diagnosis or a disease cause.

This completes the local comparison-practice product only. It does not record a successful search, finish the missing Monday activity or certify official PLTW completion.

Use a blank statement frame

From [actual saved record or supplied illustrative practice], [hit labels] have [recorded identity], [recorded E-value] and [recorded coverage]. These measures support [qualified comparison, or why the comparison remains uncertain]. [State a limit.]

If actual measures conflict or information is missing, state what remains uncertain instead of forcing a winner.

Read this first

Driving question: What do the recorded numbers support about two compared hits, and what remains uncertain?

What you already know: On Monday, you saved your input source, search settings and actual result or unfinished step. Reopen that record. The tutorial checked the ; it did not validate the case identification.

New idea: Read , and E-value together before writing a qualified comparison. Smaller E-values indicate greater in the relevant search context. No universal cutoff or disease-identification guarantee follows.

Visual or model: F1. F1. Blank record layout, not search data. The separate A/B practice is labeled illustrative. What to notice: Keep each hit's three measures in the same row and the source/context beside the table.

Choose two usable hits from your saved Monday record. If unavailable, use the supplied A/B illustrative practice and label that route. Keep the actual missing or unfinished step noted separately in the same record.
Read the definitions of query, hit, , and E-value. Use the notation aid before copying a small E-value.
Fill both rows of the comparison table from the chosen evidence. Keep the source and context with the actual column labels. Do not invent a missing value.
Compare , and E-value together. Explain what the recorded measures support. If the measures conflict or information is missing, state the uncertainty instead of forcing a winner.
Revise the statement so it cites all three recorded measures and stays within the claim limit. Keep illustrative practice separate from an actual search result.
Check the two rows, source label and statement. Submit one PDF through assignment 8520302476, unless your paper was collected in class. Keep the record for later work.

Real biomedical example: Report what the comparison supports without claiming a diagnosis or disease cause. Source: BLAST FAQ: E-value.

What the evidence supports: E1 defines the measures. Actual saved rows or labeled E2 practice supply the values. F1 organizes the record, and E3 identifies the one product.

What it cannot prove: The comparison cannot establish an organism's identity, a diagnosis or a disease cause. This completes the local comparison-practice product only. It does not record a successful search, finish the missing Monday activity or certify official PLTW completion.

Vocabulary:

• Query: The input sequence being compared with database entries.
• Hit: A database entry returned with an to the query.
• : The percentage of positions in the reported with identical letters. It does not describe unaligned parts of the query.
• : The percentage of the query represented in the or alignments reported for that hit. Keep the actual column label and comparison context.
• E-value: The expected number of alignments with that score or better arising by chance for that database search. It is an expected count, not a probability or percent.

Use it now: Use the supplied table and definitions to complete the same two-hit comparison and qualified statement.

Go further, optional: The required definitions, table, notation aid and practice values are supplied here. The NCBI links provide further explanation.

Evidence set and decision

E1 · Measure guide

Use the supplied definitions for identity, and E-value. E-value is an expected count for the search, not a probability or percent.

Limit: The comparison cannot establish an organism's identity, a diagnosis or a disease cause.

E2 · A/B practice

Illustrative practice values, not a run or case result. A: identity 99%, E-value 2e-60, coverage 98%. B: identity 99%, E-value 0.4, coverage 11%. Assume the same illustrative comparison context for A and B. No sequence, organism or disease is supplied.

Limit: This completes the local comparison-practice product only. It does not record a successful search, finish the missing Monday activity or certify official PLTW completion.

E3 · One product

One two-hit comparison table and a revised, qualified statement citing , E-value and . Submit the table and revised statement together as one PDF to Schoology assignment 8520302476 by Tuesday, September 15 at 11:59 PM. If your paper was collected in class, do not upload it again. Keep your original record.

Limit: This card states the task. It is not evidence of a search result or biological conclusion.

MI15 comparison practice · Simulated classroom evidence scenario

Your role: student checking a comparison record

Decision: Choose the response that fits the evidence route you actually have. This discussion revises the same table and statement.

• Use the recorded measures together and write a qualified comparison.
• Treat 99% identity as proof of the organism's identity or disease cause.
• If actual records are unusable, complete the labeled A/B skill practice and note the unfinished investigation step.

Response: One two-hit comparison table and a revised, qualified statement citing , E-value and . Submit the table and revised statement together as one PDF to Schoology assignment 8520302476 by Tuesday, September 15 at 11:59 PM. If your paper was collected in class, do not upload it again. Keep your original record.

Claim ceiling: The comparison cannot establish an organism's identity, a diagnosis or a disease cause.

Math moment

Formula or setup

2e-60 means 2 × 10^-60. Retain the recorded notation. Do not round a small value to zero or turn it into a diagnostic probability.

Worked parallel example

Illustrative practice values, not a run or case result. In the same illustrative comparison context, A and B both have 99% identity. A has greater (98% versus 11%) and a smaller E-value (2e-60 versus 0.4), supporting a stronger reported sequence-similarity comparison for A. This does not establish an organism's identity, a diagnosis or a disease cause.

Units and reasonableness

and are percentages. E-value is an expected count, not a probability or percent. Keep the recorded column label and context.

Try it with today's data

Read the three measures from your chosen two rows. No new calculation or numeric threshold is required.

Watch the trap

Students often think One strong-looking number proves an organism's identity.. The trap: describes aligned positions. Use all three recorded measures and context, and keep the conclusion within the stated limit.

Illustrative A/B comparison model

Two-hit comparison table and qualified statement

Completes: One two-hit comparison table and a revised, qualified statement citing percent identity, E-value and query coverage.

Hit label	Percent identity	E-value	Query coverage
A	99%	2e-60	98%
B	99%	0.4	11%

Why this matters

This model shows the level of evidence and organization needed to complete: One two-hit comparison table and a revised, qualified statement citing percent identity, E-value and query coverage.

Build yours step by step

Choose two usable hits from your saved Monday record. If unavailable, use the supplied A/B illustrative practice and label that route. Keep the actual missing or unfinished step noted separately in the same record.
Read the definitions of query, hit, percent identity, query coverage and E-value. Use the notation aid before copying a small E-value.
Fill both rows of the comparison table from the chosen evidence. Keep the source and context with the actual column labels. Do not invent a missing value.
Compare percent identity, query coverage and E-value together. Explain what the recorded measures support. If the measures conflict or information is missing, state the uncertainty instead of forcing a winner.
Revise the statement so it cites all three recorded measures and stays within the claim limit. Keep illustrative practice separate from an actual search result.
Check the two rows, source label and statement. Submit one PDF through assignment 8520302476, unless your paper was collected in class. Keep the record for later work.

Keep the practice label

This completes the local comparison-practice product only. It does not record a successful search, finish the missing Monday activity or certify official PLTW completion.

See the full worked example

Portal terms

CER:: Claim, Evidence, Reasoning: make a claim, back it with evidence, explain your reasoning.
SOP:: Standard Operating Procedure, the exact steps to follow (especially in a lab).
Tracker:: Your PLTW progress log where you record completed evidence.
myPLTW:: The PLTW course site where you do the online activities. Find it in Clever with your Microsoft sign-in, right next to Schoology.

Practice: try a question, then check your answer▸

Claim ceiling for this check: The comparison cannot establish an organism's identity, a diagnosis or a disease cause.

Quick self-check · commit, then reveal

Illustrative practice values, not a BLAST run or case result. Compare A and B in the supplied table. What do their recorded measures support, and what do they not establish?

Your answer (commit before you see the key)

How sure are you?

Write an answer and pick a confidence to unlock the key.

Missed class or ready for more?▸

Where this leads: careers

What today's skills lead to. These are real health-science careers this course builds toward. Tap one to see, on the US Department of Labor's O*NET site, what the job actually involves, what it pays, and how fast it is growing.

Genetic CounselorHelp families understand inherited risk and testing options.ImmunologistStudy how the body defends itself and design vaccines and therapies.OncologistDiagnose and treat cancer at the cell and DNA level.Biological TechnicianRun molecular and genetic lab techniques in research and biotech.

What to do if you were absent

Complete the same comparison practice

Today's definitions and supplied A/B comparison practice

If MR. MENDOZA is absent

Class still runs. Complete the online activity above (it's self-guided). Need the concept taught without a teacher? Use this authoritative explainer:

Definitions, comparison record and A/B practice

How I will check this work

Record two hits with all three measures and their source/context.
Explain the comparison using the supplied definitions and a stated limit.
Submit one labeled comparison product without claiming practice is an actual search.

The comparison cannot establish an organism's identity, a diagnosis or a disease cause. Use the Schoology assignment linked above to submit it.

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