3.14-3.39 Inheritance

What is a genome?

The entirety of an organism’s DNA is known as its genome

What is an allele?

Different versions of the same type of gene resulting in different versions for a particular trait

What is a dominant allele?

If one copy of this type of allele present its phenotype will always be expressed

What is a recessive allele?

Needs two copies of this type of allele to be present its phenotype to be expressed

What is a phenotype?

Physical expression of genotype resutling in a physical characteristic

What is a genotype?

The combination of alleles for a gene that an organism possesses

What is a homozygous recessive?

When two alleles for a gene are identical

What is a heterozygous?

When two alleles for a gene are different

What is a gene?

A section of a molecule of DNA

What is the name for the square we use to calculate inheritance probabilities?

Punnet squares

What does each gene within the genome code for?

Each gene codes for a particular sequence of amino acids

What do sequences of amino acids form?

They form different types of proteins

Fill in the gap: genes control our [ ] as they code for proteins that play important roles in what our cells do

Characteristics

Name four types of protein in the body:

1. Structural proteins (e.g. collagen in skin)

2. Enzymes

3. Hormones

4. Antibodies

In the nucleus of a cell, the DNA double helix supercoils to form structures called…?

Chromosomes

When are chromosomes only visible?

Chromosomes are only visible during cell division

How many pairs of chromosomes do ordinary human bdy cells contain?

23 pairs (i.e. 46 chromosomes in total)

How is a diploid number often shown?

2n

One chromosome from a pair is inherited from each parent. What is each chromosome pair called?

Each chromosome pair is called a homologous pair

How many pairs of chromosomes do dogs have?

39 pairs

How many pairs of chromosomes do rice plants have?

12 pairs

What is the full name of DNA? [Spell it twice].

Deoxyribonucleic acid. Deoxyribonucleic acid.

What is DNA and what is it made up of?

DNA is a polymer made up of two strands coiled around to make a double helix

What are the strands formed from?

A sugar phosphate backbone with bases

What 4 bases are in a sugar phosphate backbone?

1. Adenine (A)

2. Thymine (T)

3. Guanine (G)

4. Cytosine (C)

How are the 4 bases bonded together?

Through complementary base pairing. Adenine pairs with Thymine, Guanine pairs with Cytosine.

What two processes rely on these base-pairing rules?

Cell division and protein synthesis

What is the full name of RNA?

Ribonucleic acid

What is RNA and what is it made up of?

RNA is a polynucleotide as it is made up of many nucleotides linked together in a long chain

What do RNA nucleotides never contain and what do they have instead?

They never contain the nitrogenous base thymine (T), instead they have uracil (U)

RNA molecules are [ ] made up of [ ] [ ]

RNA molecules are only made up of one polynucleotide

Name 3 specific types of RNA molecule:

1. Messenger RNA (mRNA)

2. Transfer RNA (tRNA)

3. Ribosomal RNA (rRNA)

What does mRNA do?

mRNA is the transcript copy of a gene that encodes a specific polypeptide

What is tRNA involved in?

tRNA is involved in protein synthesis

What does rRNA form part of?

rRNA forms part of a ribosome

What are the two main differences between RNA and DNA?

1. RNA is single-stranded

2. RNA contains uracil instead of thymine

What two stages is the process of turning a gene into a specific sequence of amino acids split into?

Transcription and translation

What is transcription?

The process where a section of DNA is transcribed to produce a complementary single strand of mRNA

What is translation?

The process where an mRNA molecule is decoded at a ribosome to produce a chain of amino acids

What is transcription located in the cell? Name the specific part.

Nucleus

What happens first in transcription in DNA?

Part of the DNA molecule unwinds as H bonds between complementary base pairs break

What is the exposed DNA strand used during transcription?

The template strand

What is the role of free mRNA nucleotides in transcription?

They bind to complementary nucleotides on the exposed DNA template strand and join together to form mRNA

How does mRNA exit the nucleus?

Through a pore in the nuclear envelope

What is the relationship between mRNA product and original DNA gene?

The single stranded mRNA is a complementary copy of the DNA code from the template strand

Where in the cell does translation take place?

In the cytoplasm, specifically, on a ribosome

What does mRNA attach to during translation?

A ribosome in the cytoplasm

What is tRNA?

A transfer RNA which carries a specific amino acid to the ribosome matching its anticodon to mRNA

What is a codon?

A triplet of consecutive bases on an mRNA strand that codes for a specific amino acid

What is an anticodon?

A triplet of unpaired bases at one end of a tRNA molecule complementary to an mRNA codon

What is the relationship between an anticodon and an amino acid?

Each specific anticodon on tRNA corresponds to one specific amino acid carried at its other end

What is the name of the bond formed between adjacent amino acids?

Peptide bond

What signal terminates translation?

A ‘stop’ codon on the mRNA molecule

What does the amino acid chain do finally for modification?

The amino acid chain folds and is modified to form a functional protein molecule

What is the primary function of H bonds in DNA during transcription?

They break to allow the two strands of DNA to separate and expose the template strand

What is the difference between the output of transcription and the output of translation?

Transcription produces an mRNA molecule, whereas translation produces an amino acid chain (a protein)

What are the sequence of events during translation?
1. mRNA attaches to [ ]

2. [ ] [ ] pair with [ ] [ ]

3. [ ] bonds form between [ ] acids

4. stops at ‘stop’ [ ]

1. mRNA attaches to ribosome

2. tRNA anticodons pair with mRNA codons

3. peptide bonds form between amino acids

4. stops at ‘stop’ codon