DNA, Genetics & Genetic Engineering Deck (1)

jjjj

What is DNA?

Deoxyribonucleic acid; the genetic material that carries hereditary information and codes for proteins.

What is RNA?

Ribonucleic acid; a nucleic acid involved mainly in protein synthesis.

What is a gene?

A section of DNA that codes for a specific protein/characteristic.

What is a genome?

The complete genetic material of an organism.

What is a chromosome?

A thread-like structure made of DNA and proteins that carries genetic information.

What is chromatin?

A thread-like network of DNA and proteins that condenses to form chromosomes during cell division.

What is nuclear DNA?

DNA contained in the nucleus and associated with chromosomes.

What is mitochondrial DNA (mtDNA)?

DNA found in mitochondria; it is circular, smaller than nuclear DNA and maternally inherited.

What is a nucleotide?

The basic unit/monomer of DNA or RNA.

What are the three parts of a DNA nucleotide?

Deoxyribose sugar, phosphate group and nitrogenous base.

What is a nitrogenous base?

The nitrogen-containing component of a nucleotide.

Name the four nitrogenous bases in DNA.

Adenine (A), thymine (T), cytosine (C) and guanine (G).

What are the four bases in RNA?

Adenine, uracil, cytosine and guanine.

What is a polymer?

A large molecule made from many repeating smaller units called monomers.

Why is DNA called a polymer?

It consists of many repeating nucleotides.

What is the double helix?

The twisted, two-stranded structure of DNA.

What forms the sides/backbone of DNA?

Alternating deoxyribose sugars and phosphate groups.

What forms the rungs of the DNA 'ladder'?

Pairs of nitrogenous bases.

Which bases pair in DNA?

Adenine pairs with thymine; guanine pairs with cytosine.

What holds complementary bases together?

Weak hydrogen bonds.

What is complementary base pairing?

The specific pairing of A with T and G with C.

What is the base-pairing rule?

A pairs with T and G pairs with C in DNA.

What is the structure of DNA?

Two nucleotide strands twisted around each other to form a double helix. When untwisted, it resembles a ladder.

What is coding DNA?

DNA that contains sequences determining the amino-acid sequence of a protein.

What does coding DNA determine?

Which protein is made, its structure and therefore its function.

What can a mutation in coding DNA affect?

The structure and function of the resulting protein.

What is non-coding DNA?

DNA that does not directly code for a protein.

What is another term sometimes used for non-coding DNA?

'Junk DNA' — although much non-coding DNA has known or suspected functions.

Give three functions/types of non-coding DNA from the notes.

Structural DNA; genes for functional RNA; introns.

How can non-coding DNA regulate genes?

It can control when, where and how much a gene is expressed.

What is gene regulation?

Control of when, where and how much a gene is expressed.

Why is gene regulation important?

It ensures proteins are produced at the correct time, place and amount.

What are introns?

Non-coding sections of a gene that are removed from the RNA transcript before translation.

What are exons?

Sections of a gene that remain in mature mRNA and are translated.

Which are translated: introns or exons?

Exons.

What is a telomere?

A protective DNA region at the end of a chromosome.

What happens to telomeres as cells divide?

They gradually shorten.

What happens to telomeres over a person's life?

They generally become shorter.

What is endosymbiosis?

A mutually beneficial relationship in which one organism lives inside another; mitochondria are thought to have originated from free-living bacteria.

Why does mitochondrial DNA support the endosymbiotic theory?

Mitochondria have their own circular DNA and other bacterial-like characteristics.

Who were Watson and Crick?

Scientists who developed the double-helix model of DNA.

What contribution did Rosalind Franklin make?

She produced X-ray diffraction data that provided important evidence about DNA's structure.

What contribution did Maurice Wilkins make?

He worked with X-ray diffraction data and shared data relevant to DNA structure.

How did multiple scientists contribute to discovering DNA structure?

X-ray diffraction evidence from Franklin and Wilkins and model-building by Watson and Crick contributed to the double-helix model and base-pairing rule.

Why was Watson and Crick's model important?

It explained how DNA could store genetic information and replicate.

Why is the Watson-Crick model called a scientific model?

It represents DNA structure using experimental evidence and can be tested and refined.

Why was discovering the DNA code scientifically important?

It helped explain inheritance, protein synthesis and genetic disorders.

Why is DNA considered an everyday concept?

It is used in medicine, forensics, ancestry testing and genetic research.

Why was there competition among scientists studying DNA?

Scientists wanted to be first to explain its structure and function.

Give two limitations of physical DNA models.

They may not be to scale and are static, so they cannot fully show dynamic processes such as replication.

What should you be able to label on a DNA diagram?

Sugar, phosphate, nitrogenous bases, hydrogen bonds, nucleotide, complementary base pairs and the two strands.

What does a DNA ladder model show?

Sugar-phosphate backbones form the sides and paired nitrogenous bases form the rungs.

What are the three main types of RNA?

mRNA, tRNA and rRNA.

What does mRNA stand for?

Messenger RNA.

What does tRNA stand for?

Transfer RNA.

What does rRNA stand for?

Ribosomal RNA.

Where is RNA found?

In the nucleus, cytoplasm and ribosomes.

What sugar is found in RNA?

Ribose.

What base replaces thymine in RNA?

Uracil.

What does mRNA do?

Carries the genetic code from DNA to a ribosome for protein synthesis.

What does tRNA do?

Carries specific amino acids to the ribosome.

What does rRNA do?

Forms part of the structure of ribosomes.

What is an RNA codon?

A sequence of three bases on mRNA that specifies an amino acid or a stop signal.

What is an anticodon?

A three-base sequence on tRNA complementary to an mRNA codon.

What molecule carries codons?

mRNA.

What molecule carries anticodons?

tRNA.

What is one major difference between DNA and mRNA?

DNA is double-stranded; mRNA is single-stranded.

Give another difference between DNA and mRNA.

DNA contains thymine; mRNA contains uracil.

Where is mRNA formed?

In the nucleus/nucleoplasm during transcription.

Where does tRNA function?

In the cytoplasm at the ribosome.

What is the ribosome made partly of?

rRNA and proteins.

How many amino acids are used to build proteins?

20 standard amino acids.

What is DNA replication?

The process by which DNA makes an identical copy of itself.

When does DNA replication occur?

During interphase, before cell division.

Why does DNA replicate before cell division?

So each daughter cell receives the same genetic information.

What enzyme separates DNA strands during replication?

DNA helicase is generally responsible for unwinding/separating the strands.

What happens first in DNA replication?

The DNA double helix unwinds and the strands separate.

What acts as a template during DNA replication?

Each original DNA strand acts as a template for a new complementary strand.

What happens during complementary base pairing in replication?

Free nucleotides pair with exposed bases: A-T and G-C.

What forms the new DNA backbone?

Sugar and phosphate groups link the nucleotides together.

What are the products of DNA replication?

Two DNA molecules, each containing one original strand and one newly formed strand.

What does semi-conservative replication mean?

Each new DNA molecule contains one original strand and one newly synthesised strand.

Why is DNA replication important?

It ensures genetic information can be accurately passed to new cells.

What is protein synthesis?

The process by which cells use genetic information to produce proteins.

Where does transcription occur?

In the nucleus.

Where does translation occur?

At ribosomes in the cytoplasm.

What are the two stages of protein synthesis?

Transcription and translation.

What is transcription?

The copying of the genetic information from a DNA template strand into mRNA.

Why does transcription occur?

To make a portable mRNA copy of the genetic instructions that can leave the nucleus.

Which DNA strand is used during transcription?

One DNA strand acts as the template.

What enzyme is involved in transcription?

RNA polymerase.

What does RNA polymerase do?

It unwinds DNA, breaks hydrogen bonds and joins complementary RNA nucleotides to form mRNA.

What is the product of transcription?

mRNA.

What happens to the mRNA after transcription?

It leaves the nucleus through a nuclear pore and travels to a ribosome.

What is a nuclear pore?

An opening in the nuclear membrane through which substances such as mRNA can pass.

What does mRNA attach to?

A ribosome.

What is translation?

The process in which the ribosome uses mRNA codons to assemble amino acids into a polypeptide.

What does a codon specify?

A particular amino acid or a stop signal.

What does tRNA bring to the ribosome?

A specific amino acid.

What does the tRNA anticodon do?

It pairs complementarily with the corresponding mRNA codon.