Category: Year13 Biology

Question: DNA profiling is being used as part of an international research project to identify twenty thousand marine fish species by the year 2010. Scientists will identify the sequence of bases in a specific region of mitochondrial DNA which does not show much variation within species, but between species is very different. The DNA is sourced from muscle tissue using standard DNA extraction techniques.

Discuss the human need or demand for DNA profiling technology in relation to identifying marine fish species.

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[‘MERIT’ ANSWER]

This use of DNA profiling enables fish species to be accurately identified. This allows biodiversity / conservation issues to be addressed, Evolutionary links to be identified.

Data on fish species will also enable fish quotas/stocks to be ascertained. DNA profiling is faster and more accurate than any other method of identification so that data on fish species can enable fish quotas/stocks to be ascertained to ensure they are sustainable.

[‘EXCELLENCE’ ANSWER -add these statements to MERIT answer]

This use of DNA profiling is justified as it enables fish species to be identified faster and more accurately than any other method. This allows biodiversity and conservation issues to be addressed more accurately, as data on each fish species is more accurate. Without the use of DNA profiling different species of fish that look similar may have been misidentified and this would have made it appear that there were more of a species present than was actually the case.

When the stocks of a fish species are able to be quickly and accurately determined it helps to ensure that appropriate management strategies are implemented to maintain a sustainable catch.

Elements, compounds and mixtures

Chemical substances consist of either elements in their pure form or combinations of elements. An element cannot be physically broken down into simpler substances. Different elements have different properties. Elements comprise metals and non-metals. Iron is an example of metal. Non-metals include hydrogen and oxygen. Elements combine to form compounds or mixtures. Compounds are combinations of elements joined chemically, in fixed proportion. Compounds can not be physically separated into their elements. A mixture can be separated into their elements. Mixtures are separated by processes such as filtration, sieving and evaporation. All of these involve a physical change. We can determine whether a substance is pure or not by trying to separate it physically.

공부의 신은 한국에만 있는게 아니다. 뉴질랜드에서는 NCEA와 CIE 그리고 그외의 시험을 어떻게 준비해야 할까?

1. 시험기출문제 적극 활용 – 리허설 없이는 무대에 설수 없다
2. 마무리를 잘해라. 공부시작할때의 의지보다는 끝 맺을때의 의지가 더 중요한법이다.
3. 수업시간에 집중해라. 만화책, 핸드폰, 잡담.. 봐서 알지만 선생님 눈에는 안타까울 뿐이다. 한번만 잘들어도 집에가서 복습이 10배는 쉬워지는 법이다. 고등학교에서의 훈련은 대학생활에 좋은 거름이다.
4. Internal assessment test볼때는 교과서만 읽을게 아니라 문제를 풀어봐라.
5. 글을 체계적으로 쓰는 연습하기 – 용어, 확실한 표현법, 그리고 결론맺음이 점수다.
6. 개념부터 차근차근. 개념이 흔들리면 무슨글을 써도 의미가 다르다. 점수가 영 안나온다면.. 잦은 실수 탓이아니라 개념이 튼튼하지 못한탓.
7. 목차는 중요하다. 목차에서 키워드를 찾고 흐름을 찾고 목차를 외워라.
8. 체력은 .. 공부를 할 수 있는 힘이다. 시험도 체력부족하면 악력 그리고 집중력이 딸려서 포기하게 된다.
9. 메모리 트리, 콘셉맵, 마인드 맵을 꼼꼼히 그려서 자신만의 교과서를 만들어라.

어린아이나 큰 어른이나 집중력은 테레비 볼때가 가장 높지 않은가 싶다. 그렇다면 공부를 테레비많큼 재밌게 보면 된다는 말이 되지만 글은 역시나 판타지 소설이나 써스펜스 소설이 아니면 재미가 없다.

학습 집중력이 높다면 오랬동안 책상앞에 앉아 있지 않아도, 필기정리만 해도 금방 점수가 오른다. 그렇다면 학습 집중력은 어떻게 향상 시킬까. 내 개인적인 생각이 아니라 그동안 연구논문에 거론되었던 몇가지를 적어본다.

Continue reading “근데 쌤.. 집중이 안되요..”

공부는.. 해야만 하는 것일수도 있고, 안해도 되는것일수도 있다.

공부는 즉, 선택이다. 공기에대해서 모른다고 해서 공기가 없어지는 것은 아니다. 다만, 남보다 조금 야무지지 못하고 미련한 면을 보일뿐이다.

공부하는 사람에게 가장 필요한 것은 무엇일까?

Continue reading “지금 너에게 필요한건?”

Here are the questions related to PROTEIN SYNTHESIS for Lv3 Biology external exam. Only some questions are answered.

Q1. The information carried by DNA controls protein synthesis. Protein synthesis includes transcription and translation. Discuss the reasons why both transcription and translation are necessary for protein synthesis.

ANSWER

Transcription: mRNA is synthesized using DNA (or a section of DNA/ allele) as a template. Must occur in the nucleus because DNA is confined there – in this way, DNA is protected. mRNA is needed so that the instructions carried by DNA (genetic code) can be delivered to the ribosome and expressed as a specific protein.

Translation: mRNA carries the code (sequence of bases) from DNA to the ribosome, where amino acids are joined to produce a protein and polypeptide. mRNA attaches to a ribosome in the cytoplasm, tRNA molecules bring amino acids (their order determined by the anticodon of the tRNA which matches the codon of the mRNA. Amino acids are joined on the ribosome (peptide bonds). tRNAs ensure that the genetic code is accurately translated into a sequence of amino acids in the polypeptide. Translation ensures that the instructions on mRNA are accurately interpreted, and protein beings and ends at the correct points.

DNA carries the genetic code. It is kept safe in the nucleus (protected by the nuclear envelope and histone proteins). However, to be expressed (genes used to make proteins), DNA must unwind. mRNA is made as an expendable, temporary carrier of genetic information. It is used to make the polypeptides. mRNA has a relatively short life expectancy and more mRNA can be manufactured when needed. Transcription must precede translation, but both are needed if a protein is to be produced.

Continue reading “(Q)NCEA L3 BIOLOGY: Protein Synthesis”

Discuss how DNA replicates. In your discussion, you should explain:

• How replication begins.
• The roles of the main enzymes involved.
• Leading and lagging strands
• Okazaki fragements
• The source of materials for replication

(Remember, there are 5 parts to this question)

1. Replication begins when the two strands of DNA separate. This occurs by breaking the hydrogen bonds between base pairs and is carried out by the enzyme helicase.

(Scholarship: This begins at specific points along the DNA molecule called replication origins. At these points, replication initiation proteins recognize the unique base sequence and allow attachment of the helicase enzyme. Eukaryote chromosomes may have many ‘origins’.)

2. Enzymes involved include –

1) helicase: unwinds DNA strands (breaks hydrogen bonds between base pairs) and splits the two strands apart.

2) Gyrase: releases the tension in DNA strands that result from the unwinding processes.

3) RNA polymerase: synthesizes and attaches short RNA primers that allow attachment of DNA polymerase III

4) DNA polymerase III: extends RNA primers by addition of new DNA nucleotides, the exisdting strand acts as a template (complementary base is added), and on one side of the DNA molecule this creates Okazaki fragments

5) DNA polymerase I: replaces RNA primers with DNA

6) Ligase: joins Okazaki fragments, completing the lagging strand.

3. On the 3′ to 5′ DNA strand, DNA polymerase III adds nucleotides continuously : called leading strand.  On the 5′ to 3′ DNA strand, DNA is added in short lengths (Okazaki fragements); these are later joined by ligase – called lagging strand.

4. Okazaki fragments are short length of DNA (1000 to 2000 nucleotides long), formed because DNA polymerase III only synthesizes new strands in the 5′ to 3′ direction. Anti-parallel nature of DNA.

5. Materials required by this process (mostly enzymes and nucleotides) originate in the cytoplasm where they are synthesized by enzyme specific to this function. This occurs during interphase(mitosis).

6. DNA replication is semi-conservative. This means that the two original strands of the DNA molecule each become one of the strands in the daughter DNA molecules. This daughter molecules therefore consist of one parental and one newly synthesized strand.

Ref: AME NCEA L3, Biology workbook(2008)

Answers to Part C:

1. Describe the process of DNA replication.

DNA replication involves strands of DNA (double helical molecule with anti-parallel chains) locally unwinding to a single strand revealing free 3′ and 5’ends (via DNA helicases). DNA polymerase synthesizes new nucleotides from 5′ to 3′ end (the leading strand) and the Okazaki fragments assemble and join to the 3’end of the lagging strand. These are then linked by the enzyme ligase. The new DNA strand is rewound back into a helix.

2. DNA replication is described as a semi-conservative process. Explain what is meant by semi-conservative.

Semi-conservative replication refers to the fact that the parental DNA acts as a template for the two new strands of DNA that are synthesized. The new DNA strand consists of 50% old DNA and 50% new DNA.