Biology Unit 4 Concepts 1-3 Test

Nucleic acid

the macromolecule that holds our genetic materials (DNA)

Nucleotide

the monomer of nucleic acids

mRNA

(messanger) (intruction manual) copies instructions in DNA and carries these to the ribosomes in the cytoplasm

tRNA

(transfer) (ingredients being transferred according to instructions) binds and carries specific amino acids to the ribosome

rRNA

rRNA (ribosomal) along with proteins, make up the ribosome; also help catalyze the formation of peptide bonds

Chromosome

tightly coiled strands of DNA

Gene

a section of DNA that has instructions to code for a protein

(one chromosome can contain thousands of genes linked together)

RNA primer

short pieces of RNA to help get the DNA polymerase started

Okazaki fragments

short pieces of DNA on the lagging strand

Base pairing rules of DNA (Chargaff)

A's bind to T's and C's bind to G's

Nitrogen Bases for DNA

Adenine, Guanine, Cytosine, and Thymine

Nitrogen Bases for RNA

Adenine, Guanine, Cytosine, and Uracil

Double Helix

Structure of DNA:

Sugar + Phosphate “backbone”

Nitrogen bases bond with weak hydrogen bonds

All other bonds are strong covalent bonds

Antiparallel

The strands run in opposite directions

Reading DNA

Phosphate end is always the 5’ end

Deoxyribose sugar end is always the 3’ end

Sugar for DNA

Deoxyribose sugar

Protein synthesis

the process of reading the instructions in DNA to make a polypeptide

1. Transcription (DNA makes a copy of DNA)

2. Translation (Instructions for making proteins)

DNA —> RNA —> protein

RNA Structure

single strand of nucleotides with exposed bases

DNA Replication

When a cell is ready to divide it needs to make a copy of its DNA

Occurs in nucleus during Synthesis phase

DNA Replication process

1. Helicase unzips the DNA

2. DNA polymerase adds complementary nucleotides to template strands (works in 5’ to 3’ direction ONLY)

   1. Primase: makes short RNA primers

   2. DNA Polymerase

   3. DNA Ligase: seals gaps in DNA + connects pieces

Leading Strand

made in the 5’ to 3’ direction, needs ONE RNA primer, continuous

Lagging Strand

made in the 3’ to 5’ direction, creates okazaki fragments joined by DNA ligase, needs MANY RNA primers

Semi-Conservative Replication

• Each parent strand is now a template (pattern) that determines the order of the new bases

• Forms a “complementary” strand to the original strand

• The newly synthesized double helix is a combination of one “old” (or original) and one “new” DNA strand

Polypeptide

a chain of amino acids that can bind to others and fold into a protein

Where are proteins made?

ribosomes

Transcription

the process of turning DNA into mRNA

Occurs in nucleus DNA never leaves the nucleus

1. RNA polymerase binds to DNA and is unzipped

2. RNA polymerase uses complementary base-pairing rules to match RNA nucleoides with exposed DNA nucleotides

3. Release the completed mRNA molecule

4. DNA zips back up and the mRNA leaves the nucleus and enters the cytoplasm

Creation of RNA vs DNA

RNA is made in 5’ to 3’ direction

DNA is read in the 3’ to 5’ direction

RNA splicing

• This process removes introns and policies exons together

  • Can create different combinations of exons and thus make multiple polypeptides from 1 gene

• 5’ cap (G cap, a modified guanine) is added to the 5’ end —> facilitates binding to a ribosome

• Poly A tail (50-520 As) is added to the 3’ end —> helps the mRNA leave the nucleus

Introns

non-coding region

Exons

coding regions

Genetic code

code of instructions for how to make proteins

Codon

a set of 3 nucleotides on the mRNA

Anticodon

"complementary" 3 nucleotides on tRNA

Amino acid

monomer for making proteins, held together by peptide bonds

Translation

the process of turning mRNA into proteins

Occurs in ribosome

1. mRNA attaches to the small subunit of the ribosome

2. Ribosome reads mRNA codons always in the 5’ to 3’ direction starting at the AUG codon

3. tRNAs pick up and drop off amino acids that match to each codon

4. Ribosome binds amino acids together with peptide bonds

5. When the “stop” codon is read, the ribosome releases the completed polypeptide chain

Epigenetics

the study of changes in gene expression that are heritable

Central dogma

DNA, which is located in the nucleus, cannot leave but proteins are made in the ribosomes

Theory stating that genetic information flows only in one direction, from DNA, to RNA, to protein

Diploid

a cell with 2 full sets of chromosomes, a set from each parent

Haploid

a cell with 1 full set of chromosomes, a combination of chromosomes from both parents

Karyotype

a diagram that shows the number and visual appearance of chromosomes in a cell

Meiosis

the process of cell division that makes gametes in the gonads

Sexual reproduction

fuses the genetic information (gametes) from two parents to produce offspring that are a genetic mixture of both parents

Fertilization

the actual fusion of egg and sperm to form a zygote

Homologous chromosomes

chromosome pairs that have the same types of genes

Sister chromatids

2 identical copies of the same chromosome

Somatic cell

a body cell and is diploid

Gamete

a sex cell and is haploid

Autosomes

carry the traits that make us who we are

Sex chromosomes

determine our biological sex

Meiosis

the process of cell division that makes gametes in the gonads (ovaries in females, testes in males)

Before Meiosis I

Interphase: growth phase of the cell cycle

• G1 phase: cell grows and makes proteins

• S phase: DNA replication occurs, doubling the number of chromosomes

• G2 phase: more cell growth and protein synthesis

At the end of interphase, the cell has 2 duplicated copies of every chromosome

Meiosis I

the process of separating homologous chromosomes

Prophase I

Metaphase I

Anaphase I

Telophase I (and cytokinesis)

creating 2 haploid daughter cells

Prophase I (PMAT)

• Nuclear membrane breaks down

• Centrioles separate and make spindle fibers

• Homologous chromosomes pair up and become visible

• Tetrad: cluster of 4 chromatids

Metaphase I (PMAT)

Homologous chromosomes are lined up in the middle of the cell in pairs

Anaphase I (PMAT)

• Homologous chromosomes pairs separate, one chromosome (2 sister chromatids) pulled away to each side of the cell

• Sister chromatids remain attached

Telophase I (PMAT)

• Chromosomes gather at the poles (opposite ends)

• Nuclear membranes may reform

Cytokinesis I (PMATC)

• cytoplasm divides into 2 cells

Meiosis II

the process where sister chromatids are separated

Prophase II

Metaphase II

Anaphase II

Telophase II (and cytokinesis)

resulting in 4 genetically unique haploid daughter cells

Prophase II (PMAT)

• Nuclear membrane breaks down (if they reformed)

• Spindle fibers form and attach to the centromeres of the sister chromatids

Metaphase II (PMAT)

Sister chromatids line up in the middle of the cells single file

Anaphase II (PMAT)

Sister chromatids separate and are pilled away from each other to each side of the cells

Telophase II (PMAT)

• Nuclear membranes form around each set of chromosome

• Spindle fibers dissolve

Cytokinesis (PMATC)

• cytoplasm divides each cell into 2 cells

Genetic Variation

• Crossing over (P1)

• Independent Assortment (pairs of chromosomes line up randomly) (M1)

• Random Fertilization

Non-disjunction

During anaphase, chromosomes may not fully separate, which can lead to genetic disorders

EX: down syndrome

Crossing over

when chromosomes get tangled and swap DNA, creating a new combination of genes

Mitosis VS Meiosis

Mitosis: creation of diploid somatic cells, throughout life, throughout body, for growth and repair, PMAT occurs once, results in 2 diploid somatic cells, axsexual

Meiosis: creation. of haploid sex cells, occurs before born (f) or throughout life (m), in ovaries and testes, to make babies, PMAT occurs twice, results in 4 haploid gametes, sexual