Gene Expression

Flashcards covering the basics of gene expression, chromosomes, protein synthesis, and cell differentiation.

What is a gene?

A length of DNA that codes for a protein.

What is an allele?

An alternative form of a gene.

What is a gene?

A length of DNA that codes for a protein.

What is an allele?

An alternative form of a gene.

What determines the sequence of amino acids used to make a specific protein?

The sequence of bases in a gene.

How do different sequences of amino acids affect protein molecules?

They give different shapes to protein molecules.

How does DNA control cell function?

By controlling the production of proteins, including enzymes, membrane carriers, and receptors for neurotransmitters.

Outline the process of how a protein is made.

The gene coding for the protein remains in the nucleus; mRNA is a copy of the gene; mRNA molecules are made in the nucleus and move to the cytoplasm; the mRNA passes through ribosomes; the ribosome assembles amino acids into protein molecules; the specific sequence of amino acids is determined by the sequence of bases in the mRNA.

Why are many genes in a particular cell not expressed?

Because the cell only makes the specific proteins it needs.

What is a haploid nucleus?

A nucleus containing a single set of chromosomes.

What is a diploid nucleus?

A nucleus containing two sets of chromosomes.

How many pairs of chromosomes are in a human diploid cell?

23 pairs.

What are chromosomes?

Arrangements of genetic information found within organisms.

What are genes?

Length of DNA that codes for genetic information and control specific characteristics.

What are homologous chromosomes?

Pairs of chromosomes with the same length and genes at the same location.

What are alleles?

Different forms of a gene that may occupy the same locus on homologous chromosomes.

What does diploid mean?

Containing two sets of each chromosome (homologous pairs) in the nucleus.

What does haploid mean?

Containing only one of each homologous pair of chromosomes in the nucleus.

What is the genetic code?

The base sequence of nucleotides in DNA or RNA that determines the order of amino acids formed.

What is a codon?

A three-nucleotide base sequence that codes for a particular amino acid.

What is protein synthesis or gene expression?

The process by which gene instructions in DNA are converted into a functional product (a protein).

What are the two main steps of protein synthesis?

Transcription and Translation.

What is transcription?

The process where DNA is unwound, and the gene (template) is copied into a complementary mRNA.

What is translation?

The process where genetic information in mRNA is translated into a sequence of amino acids in a polypeptide chain to form a protein.

Briefly explain the central dogma of molecular biology.

Genetic information flows in one direction: from DNA to RNA to proteins.

What enzyme is used in transcription?

RNA polymerase.

What base does RNA use instead of thymine?

Uracil (U).

What does tRNA do?

Transfer RNA (tRNA) brings amino acids to the ribosome that corresponds to the correct codon on mRNA.

How does a gene sequence determine protein structure and function?

The gene sequence determines the number and order of amino acids, which in turn determine its structure and function.

Give examples of proteins and their functions.

Structural proteins like collagen, enzymes like amylase, membrane carriers, and receptors.

What is cell differentiation?

The process where cell specialize, express some of their genes and make some proteins, and no longer express other genes.

What is the relation between DNA packing and gene expression?

Loosely packed DNA allows higher gene expression, while tightly packed DNA allows lower gene expression.

What happens to gene expression when stem cells differentiate?

Some genes are 'turned on,' and others are 'turned off' based on the cell's function and protein requirement.

What is a stem cell?

An undifferentiated cell that has the ability to specialize into any cell type.