Biology 1801 Final Exam- John Walker (AppState)

______ are the coding regions of eukaryotic genes

Exons

________ are intervening noncoding sequences that are removed by splicing

Introns

___________ is the removal of introns and connection of exons

Splicing

____________ ____________ allows different mRNAs and proteins to be produced from a single gene

Alternative splicing

a modified guanine nucleotide is? and enables ribosomes to bind and protects from degradation

A 5′ cap

100-250 adenine nucleotides is? and is needed for translation and protects from degradation

A 3′ poly(A) tail

___________ catalyze translation of the mRNA sequence into protein

Ribosomes

transfer RNAs (tRNA) bind to _______ ______

amino acids

An __________ ____ is a tRNA linked to its amino acid

aminoacyl tRNA

The loop at the opposite end forms the ___________

anticodon

What is the job of the tRNA in translation?

It binds to the mRNA and it transfers the specific amino acid

Ribosomes comprised of proteins & ____________ ____ in two subunits

Ribosomal RNA (rRNA)

-The small subunit holds the ______ in place
-The large subunit is where ________ bonds form

-mRNA
-peptide

The tRNAs fit into three sites in the ribosome:

1. The A site is the acceptor site for an aminoacyl tRNA
2. The P site is the peptidyl site where a peptide bond forms
3. The E site is where tRNAs without amino acids exit the ribosome

The ribosome is a molecular machine that synthesizes proteins in a three-step sequence:

1. An aminoacyl tRNA carrying the correct anticodon for the mRNA codon enters the A site
2. A peptide bond forms between the amino acid on the A-site tRNA and the polypeptide on the P-site tRNA
3. The ribosome moves down the mRNA by one codon and all three tRNAs move down one position
-The tRNA in the E site exits
-The A site is available for another tRNA to bind

_______ read 5′ → 3′ (same as synthesis)

mRNA

Amino acids are always _________ to the carboxyl end (C-terminus) of the polypeptide

added

Three phases of translation

1. Initiation
2. Elongation
3. Termination

The ___________ phase of translation begins near the AUG start codon and the small ribosomal subunit binds to the mRNA mediated by __________ __________

initiation, initiation factors

The first tRNA is called the __________ tRNA

initiator

The large ribosomal subunit binds so that the initiator tRNA is in the __ _____

P site

Initiation and elongation use ________ (___)

energy (GTP)

mRNA, t RNA and the ribosome form a complex in initiation of:

Translation

An aminoacyl tRNA binds to the codon in the __ _____

A site

The amino acid on the __ _____ tRNA is transferred to the amino acid on the __ ____ tRNA

P-site, A-site

Ribozyme _____________ peptide bond

catalyzes

_____________ occurs when the ribosome slides one codon toward the 3′ end of the mRNA and ____________ __________ help move the ribosome

Translocation, elongation factors

__________ occurs when the A site encounters a stop codon

Termination

In termination a protein called a __________ __________ enters the A site

release factor

Most proteins undergo additional processing called ______-___________ _____________

post-translational modification

Molecular ____________ speed protein folding

chaperones

____________ may add sugar, lipid, or phosphate groups

Enzymes

Sperm (n) and egg (n) haploid means one of each type of chromosome
(_____________)

fertiliztion

Zygote (2n) (diploid means two sets of each type of chromosome)
(____ __________)

Cell division

Humans cells have ___ pairs of chromosomes (=46 total)
1 of each pair from mom, 1 from dad

23

In diploid species, members of a pair of chromosomes are called _____________

homologues

Each ____________ nearly identical in size and genetic composition

homologue

What is the origin of your two sets of chromosomes?

one set is maternal and the other is paternal

Observations of __________ confirmed that plants and animals start life as single-celled ___________ and grow through a series of _____ ____________

embryos, zygotes, cell divisions

Meiosis produces reproductive cells, called __________

gametes

Mitosis produces all other cell types = _________ cells, which all chromosomes passed to daughter cells and are identical genetically

somatic

Mitosis and meiosis are usually followed by __________, which is the division of the cytoplasm into two daughter cells

cytokinesis

Basic 3 steps in cellular replication?

1. Copying the DNA
2. Separating the copies
3. Dividing the cytoplasm to create two complete cells

Eukaryotic DNA is wrapped around histone proteins called _________

chromatin

A ______________ is a single long double helix of DNA (& protein) and still counts as one after replication

chromosome

Each double-stranded DNA copy is called a ___________ and is attached at the ____________

chromatid, centromere

Chromatids attached at the centromere are called ________ ___________ and are identical copies

sister chromatids

Growing cells cycle between two phases?

1. A dividing phase called the M (mitotic) phase when chromosomes are condensed fully
2. A non-dividing phase called interphase when chromosomes are uncoiled, genes being expressed and cells spend most of their time in interphase

DNA replication occurs during the __ ________ (synthesis) of interphase when each chromosome now consist of two sister chromatids and exact copies of the same genetic information

S phase

Interphase also includes two gap phases which are?

1. G1 phase is the first gap Cells grow, perform functions
2. G2 phase is the second gap were it prepares for division

During which phase of the cell cycle does DNA replication occur?

S phase of interphase

M phase consists of two distinct events?

1. Mitosis—the division of the replicated chromosomes
2. Cytokinesis—the division of the cytoplasm

Mitosis begins when __________ condenses fully

chromatin

Sister chromatids separate to form independent ___________ chromosomes

daughter

One copy of each chromosome goes to each of the two ___________ cells

daughter

Mitosis (M phase) is a continuous process with five subphases - PPMAT

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase

During prophase chromosomes finish ___________

condensing

The spindle apparatus?

-Moves replicated chromosomes during early mitosis
-Pulls sister chromatids apart in late mitosis

Spindle apparatus is composed of _____________

microtubules

In animal cells, microtubule-organizing centers (MTOCs) are ______________, each containing a pair of ______________ and form the spindle poles

centrosomes, centrioles

_________ microtubules extend from each spindle pole and overlap with each other

Polar

________ microtubules hold spindle poles in plac

Astral

During prometaphase the nuclear ____________ breaks down

envelope

In prometaphase kinetochore microtubules attach to chromosomes at ____________

kinetochores

In prometaphase chromosomes are pushed and pulled by microtubules until they reach the ________ of the spindle

middle

During metaphase the formation of the mitotic __________ is completed and chromosomes are lined up on the _____________ ________

spindle, metaphase plate

During ____________ sister chromatids separate, and are pulled by the spindle fibers toward opposite poles of the cell

anaphase

During ___________ kinetochore microtubules shrink and motor proteins of the polar microtubules push the two poles of the cell away from each other

anaphase

During anaphase it creates two ___________ sets of _____________ chromosomes

identical, daughter

During ___________ a new nuclear envelope begins to form around each set of chromosomes and the chromosomes begin to unwind

telophase

During telophase mitosis is complete when two independent ________ have formed

nuclei

______________ typically occurs immediately after mitosis and the cytoplasm divides to form two daughter cells

Cytokinesis

During Cytokinesis in plants when vesicles from the Golgi apparatus bring membrane and cell wall components to form a _____ _______

cell plate

Cytokinesis in animals and many other eukaryotes uses a ring of ______ and _________ filaments contracts inside the cell membrane to form a __________ _______

actin, myosin, cleavage furrow

Sexual reproduction produces ___________, new gene combinations

variation

Reproductive cells called ___________ (sperm and eggs in animals) unite (= fertilization) to form a ____________ (new individual)

gametes, zygote

__________ is nuclear division that produces gametes that must contain half the chromosome number and is at fertilization, full chromosome number is restored

Meiosis

____ chromosomes determine the sex of the individual

Sex

In many animals: Females have two __ chromosomes Males have an __ ___ __ chromosome

X, X and a Y

___________ are non-sex chromosomes

Autosomes

Chromosomes of the same type are called homologous chromosomes, or ___________

homologs

A ______ is a section of DNA that influences one or more hereditary traits The different versions of a specific gene are called _________ and ___________ may contain different alleles

gene, alleles, homologs

Unreplicated chromosome

A chromosome that consists of one double-helical molecule of DNA packaged with proteins

Replicated chromosome

A chromosome after D N A replication. Consists of two identical chromatids, each containing one double-helical DNA molecule packaged with proteins

Sister chromatids

The two identical chromatids in a replicated chromosome

Homologous chromosomes (homologs)

Chromosomes that have the same genes in the same position and are the same size and shape. (Because the alleles of particular genes are often different between the homologs, homologs are not called identical chromosomes.)

Non-sister chromatids

Chromatids on different members of a homologous chromosome pair. (To be non-sister chromatids, one of the chromatids is on one homolog and the other chromatid is on the other homolog.)

Bivalent

Paired, replicated homologous chromosomes that exist during prophase one and metaphase one of meiosis

Haploid number

The number of different types of chromosomes in a cell;
symbolized n

Diploid number

The number of chromosomes present in a diploid cell (see below); symbolized 2n

Ploidy

The number of each type of chromosome

Haploid

Having one of each type of chromosome (n)

Diploid

Having two of each type of chromosome (2n)

Polyploid

Having more than two of each type of chromosome; may be triploid (3n), tetraploid (4n), hexaploid (6n), and so on

Just before meiosis begins, each chromosome in the parent cell (assume 2n) is ___________

replicated

The two attached sister chromatids are still considered a single replicated _____________ (2n)

chromosome

Meiosis consists of two cell divisions
_________ __ - the two homologs of each chromosome pair separate into two daughter cells

Meiosis I

Meiosis consists of two cell divisions
________ __ - the sister chromatids of each chromosome separate into two daughter cells
-Each of the two haploid daughter cells from meiosis I divides
-Produces four haploid cells

Meiosis II

Meiosis I is a continuous process with five distinct phases which are?

1. Early prophase I
2. Late prophase I
3. Metaphase I
4. Anaphase I
5. Telophase I

In Early Prophase I: (Meiosis)

-Nuclear envelope begins to break down
-Replicated chromosomes condensed
-The spindle apparatus begins to form
-The homolog pairs come together in a pairing process called synapsis form bivalents