Grade 12 Life Sciences - DNA, RNA, and Protein Synthesis

Flashcards based on Grade 12 Life Sciences Lecture Notes: DNA, DNA Profiling, RNA, and Protein Synthesis

What is the function of genes within a chromosome?

To group DNA.

Approximately how many genes does the human genome contain?

About 35,000 genes.

What is the role of DNA in genes?

Tells the cell what amino acids to put together to make a protein.

Describe the structure of DNA.

Two molecules arranged into a ladder-like structure called a Double Helix.

What are the subunits that make up DNA?

Nucleotides.

What are the three components of a nucleotide?

Phosphate group, pentose sugar, and a nitrogenous base.

What forms the backbone of the DNA molecule?

Phosphate and sugar.

What is the role of the bases in the DNA molecule?

Form the 'rungs' of the DNA ladder.

What are the four types of nitrogenous bases in DNA?

Adenine (A), Cytosine (C), Thymine (T), and Guanine (G).

Which base pairs with Adenine (A) in DNA?

Thymine (T).

Which base pairs with Guanine (G) in DNA?

Cytosine (C).

Why is complementary base pairing important in DNA structure?

The order of bases in one strand determines the order in the other strand.

What are codons?

Triplets of bases in DNA.

What does a gene code for?

A protein.

What makes each gene unique?

A unique sequence of bases.

How do proteins relate to phenotype?

Proteins and combinations of proteins give us a unique phenotype.

Describe the first step of DNA replication.

The double helix unwinds.

What happens to the hydrogen bonds during DNA replication?

Weak hydrogen bonds between nitrogenous bases break, and two DNA strands unzip (separate).

What role do the original DNA strands play in replication?

Each original DNA strand serves as a template on which its complement is built.

What is the outcome of DNA replication?

Two identical DNA molecules, each consisting of one original strand and one new strand.

Name two significances of DNA replication.

Important for growth, reproduction, and mutations can cause variation.

What is the main enzyme that catalyzes DNA replication?

DNA polymerase.

What is DNA Profiling?

A technique used by scientists to distinguish between individuals of the same species using only samples of their DNA.

What is a DNA fingerprint?

Unique sequence of nucleotides in a segment of DNA.

What is DNA profiling used for in solving crimes?

To provide evidence that a suspect was present at the crime scene, or to eliminate a suspect from the enquiry.

Besides solving crimes, what other problems can DNA profiling help with?

Determining a child’s paternity and maternity, which can be used in paternity suits, inheritance cases, and immigration cases.

Name the three types of RNA.

Messenger RNA (mRNA), Transfer RNA (tRNA), and Ribosomal RNA (rRNA).

What is the function of mRNA?

Acts as a template for protein synthesis and has the same sequence of bases as the DNA strand that has the gene sequence.

What is the function of tRNA?

Carries a specific amino-acid and has an anticodon complementary to the mRNA codon.

What is the function of rRNA?

Makes up an integral part of the ribosome, the protein synthesis machinery in the cell.

Name two nitrogenous bases present in both DNA and RNA.

Adenine, Cytosine and Guanine.

Name one difference between DNA and RNA regarding nitrogenous bases.

DNA contains Thymine, while RNA contains Uracil.

Name two differences between DNA and RNA regarding structure.

DNA is double-stranded, while RNA is single-stranded. DNA contains deoxyribose sugar, while RNA contains ribose sugar.

What is the function of proteins in living creatures?

Building blocks of cells, control chemical reactions, and transport materials to and from cells.

What determines the exact function of a protein?

The specific sequence of amino acids in a chain.

What is a triplet in DNA?

Each sequence of three bases in a DNA strand.

What does each triplet code for?

One of 20 amino acids, the building blocks of protein.

Where does transcription occur?

In the nucleus.

What is the template for the construction of mRNA?

One DNA strand.

Which base does RNA use instead of thymine?

Uracil (U).

Where does mRNA attach for protein synthesis?

A ribosome in the cytoplasm.

What does tRNA bind to?

Amino acids.

What is an anticodon?

A three-base sequence on tRNA that recognizes a particular mRNA codon.