BISC 120 Exam 1

Haploid cell

Contains one set of chromosomes (egg and sperm)

23 unpaired chromosomes

Number of chromosomes in haploid cell

Diploid cell

Contains two complete sets of chromosomes

46 total chromosomes arranged in 23 pairs, 22 autosome pairs, 1 sex chromosome pair

Number of chromosomes in diploid cell

Cell genome

Consists of all the DNA in a cell, can consist of a single DNA molecule (prokaryotes) or multiple DNA molecules (eukaryotes)

DNA molecules

Series of genes, packaged into chromosomes in cells

Cell division

Reproduction of cells & continuity of life and genetic material

First part of process of cell division

Single-celled organisms give rise to new organisms through cell division

Second part of process of cell division

Muticellular eukaryotes undergo embroyonic development through cell divisionT

Third part of process of cell division

Cell division continues to function in renewal and repair in fully grown multicellular eukaryotes

What happens every time growth or development happens?

Genome is copied and put into daughter cells (any cell can be taken from the body and be the same)

G1 phase of cell cycle

Growth - cell doubles in size and performs its normal daily jobs

S phase

Synthesis - cell replicates DNA and doubles genetic information

G2 phase

Final growth stage - other structures for cell division begin to assemble, chromosomes begin to condense during Prophase

Mitosis

1st part of M phase/cell division - division of the genetic material in the nucleus, separation of duplicated chromosomes, splits the copied DNA into two new nuclei through prophase, metaphase, anaphase, and telophase

Prophase

Centromeres go to either ends of cell and spindle fibers grow, chromosomes condense to help move genetic info during cell division

Metaphase

Chromosomes condense line up down the middle of metaphase plate

Anaphase

Replicated chromosomes split and move to opposite poles of the cell

Telophase

Final stage of cell division, two nuclear envelopes form around separated sets of chromosomes

Cytokinesis

Separation of daughter cells into sister cells - the physical process of cell division, splits the cell’s main fluid (cytoplasm) and outer membrane into separate cells

G0 phase

Resting state where a cell stops dividing and just does its regular work

Interphase

Cell growth, happens 90% of the time, consists of G1, G2, S, M phase

Why does genetic material becomes visible during prophase?

Strands of chromosomes condense

As cells get ready for mitosis, what happens

They take strands of DNA and wrap them around histones to move genetic material around

Sister chromatids

Each duplicated chromosome has two of them (joined copies of the original chromosome), attached along their lengths by cohesins

Centromeres

Narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached (area of similarity in the chromosome)

What happens with the two sister chromatids of each duplicated chromosome during cell division

Separate and move into two new nuclei

After chromatids are separated…

They are called chromosomes

What does eukaryotic cell division consist of

Mitosis and cytokinesis

How does DNA replication transmit genetic information

By copying the double-stranded genome so that every new cell receives an identical set of instructions

Meiosis

Produces gametes, a variation of cell division, yields non-identical daughter cells that have half as many chromosomes as the parent cell, turns one diploid cell into 4 unique haploid sex cells

Meiosis I

Pairs of matching chromosomes line up and separate into two new cells, cutting the chromosome number in half

Meiosis II

The sister strands inside halved number of chromosomes pull apart, similar to regular cell division (mitosis), resulting in four final cells

What are the components of DNA

Polymer of monomers

Polymer = big block chain

Monomer = nucleotides (the building blocks)

• nucleotides: made up of nitrogenous base, phosphate group, sugar (deoxyribose) to provide a code for constructing a protein

  • nucleotides become polymers made of nucleic acid (large, natural chemical molecules that store and pass on genetic information in all living cells)

  • composition/arrangement of nucleotides vary from one individual to the next so they act like an individual code

    • nitrogenous bases are adenine, thymine, cytosine, guanine

4 important classes of biological molecules (macromolecules)

Lipids, proteins, carbohydrates, nucleic acids

What is the structure and function of lipids

Structure - composed mostly of C, H, O but are hydrophobic and do not form long repeating polymer chains, so they are commonly ,ade of glycerol backbones attached to long hydrocarbon fatty acid chains via ester bonds

Function - provide long-term energy storage, cushion/protect organs, insulate body against heat lost, form the foundational lipid bilayer of all cellular membranes

What is the structure and function of proteins

Structure - built from chains of amino acid monomers linked togehter by peptide bonds, each amino acid has a central carbon, an amino group, a carboxyl group, and a unique side chain (R group) that folds into complex 3D shapes

Function - act as enzymes to speed up chemical reactions, build structural frameworks (e.g., collagen, keratin), transport nutrients, and drive immune defenses (antibodies)

What is the structure and function of carbohydrates

Structure - made of C, H, O (typically 1:2:1 ratio), monomers are simple sugars called monosaccharides (like glucose), which link together via glycosidic bonds to form complex chains or polymers (e.g., starch, glycogen, cellulose)

Function - act as primary, fast source of short-term energy for cells and provide rigid structural support

What is the structure and function of nucleic acids

Structure - composed of C, H, O, N, P, building blocks are nucleotides

Function - store, transmit, express genetic information, DNA holds master hereditary blueprint while RNA acts on those instructions to build essential proteins

What is the structural model of DNA

double helix

two outer sugar-phosphate backbones rotate around paired nitrogenous bases in the molecule’s interior

backbones are antiparallel (subunits run in opposite directions)

Who are Maurice Wilkins and Rosalind Franklin

Used x-ray crystallography to study molecular structure

Franklin produced a picture of the DNA molecule using the technique

Who are James Watson and Francis Crick

Enabled my x-ray crystallography pictures of DNA to deduce that DNA was helical

Pattern in the photo showed that DNA was made of two strands paired up and facing each other, forming a double helix

What is the function of the DNA structure

To contain, protect, and pass along genetic code

Protection keeps genetic code from being exposed to the environment since it has potential to react with other molecules

How many carbons does deoxyribose sugar have

5 (1’…5’)

What is the central dogma of biology

DNA —> RNA —> protein

Genetic information flows in one direction, from DNA to RNA to protein

What are the three processes of central dogma

Replication, transcription, translation

What is the replication stage of central dogma

DNA of a cell is copied to make more DNA

Enzymes unwind the double-stranded DNA and build new complementary strands

What is the transcription stage of central dogma

Genetic info from a DNA strand is copied to a mRNA molecule

RNA polymerase (an enzyme) reads the DNA template strand and builds a matching single-stranded RNA message

What is the translation stage of central dogma

Ribosomes read the RNA code in groups of three bases (codons) and tRNA brings the matching amino acids to build a growing protein chain

What do metabolic processes rely on

Proteins produced by gene expression

What does gene expression do

Process by which DNA directs the synthesis of proteins

Uses a gene to create a functional product, beginning with a protein

Builds enzymes and other proteins that carry out metabolic reactions

What are the functions of genetic information

Stored, copied, passed on, and used

What does it mean for genetic information to be stored

It is encoded in the nucleotide sequence of DNA and organized into genes and chromosomes

What does it mean for genetic information to be copied

Complementary base pairing (CG, AT) allows DNA to be accurately replicated

What does it mean for genetic information to be passed on

Replicated chromosomes can be distributed to new cells, maintaining the continuity of genetic information

What does it mean for genetic information to be used

Information in DNA can be ultimately expressed as proteins that influence cell structure and function

What is the structure of the genotype-phenotype relationship

Hierarchically bridged by DNA, RNA, protein, metabolite, and flux

What are the stages of transcription and translation

initiation, elongation, and termination

Template strand

Provides a template for ordering the sequence of complementary nucleotides in an RNA transcript, always the same strand for a given gene

Non-template strand

Coding strand, nucleotides are identical to mRNA sequence being produced for gene

What are the strands of DNA

Complementary; template and non-template

Antiparallel, sugar/phosphate backbone, hydrogen bonds, nucleotides

What is the initiation stage of transcription

All molecules are brought to the plane to build mRNA strand

Promoters

DNA regions that initiate the transcription of a gene

How long do promoters extend

Several dozen nucleotide pairs upstreamW of gene start point

What is the upstream of gene start point

3’ end of gene

Promoter region

What is the downstream of the gene start point

5’ end of gene (dictates how things are read in the cell)

What is the promotor for eukaryotes called

TATA box

What is the role of the TATA box

Forms the initiation complex

What are transcription factors

Proteins that have a shape/structure that help guide the binding of RNA polymerase

What is RNA polymerase

Enzyme and final piece of initiation that catalyzes the synthesis of RNA from DNA template

Pries the DNA strands apart and joins togehter the RNA nucleotieds

Enables transcriptors to bind upstream

What is the elongation stage of transcription

RNA polymerase moves along the DNA template strand and builds a complementary RNA molecule

During elongation, how is the template strand read

3’ to 5’ direction

During elongation, how is the RNA strand built

5’ to 3’ direction

Nucleotides are added to the 3’ end of the growing RNA molecule

What is the termination stage of transcription

Final step of RNA synthesis where the RNA strand is released from the RNA polymerase

Signaled by terminator regions on the template strand

What does the termination stage of transcription ensure

Proper regulation of gene expression and prevents the production of unwanted transcripts (mRNA sequences)

What is transcription in a nutshell

1. RNA synthesis is catalyzed by RNA polymerase

2. The RNA strand built is complementary to the DNA template strand (read 3’ to 5’)

3. RNA synthesis follows the same base-pairing rules as DNA, except that uracil substitutes for thymine

What are ribosomes

The site for translation, use the information from DNA to make proteins

Where do ribosomes build proteins

Cytasol

Outside of endoplasmic reticulum/nuclear envelope

When are ribosomes free

In the cytasol

When are ribsomes bound

Outside of the endoplasmic reticulum/nuclear envelope

What makes up ribsomes

Ribosomal proteins and ribosomal RNA

What do ribosomes specifically do in translation

Translate codons into amino acids

What is translation

Synthesis of a polypeptide from mRNA

The conversion of the nucleic acid language to the polypeptide (protein) language

What is translation based on

A triplet code

What is the triplet code in translation

Genetic instructions written as a series of three-base words

What are codons

The series of three-base words in the triplet code of translation

Genetic code

the set of rules that dictates the amino acid translations of each of the mRNA nucleotide tripletsI

In translation, how are mRNA codons used

Translated into a specific amino acid sequence of a polypeptide

In translation, what do transfer RNA molecules serve as

Interpreters

Where does translation take place

In the cytoplasm

What is the process of translation

A cell reads a messenger RNA (mRNA) blueprint to build a protein

A ribosome attaches to the mRNA and translates its message into a specific polypeptide, aided by transfer RNAs (tRNAs)

1. mRNA: The instructions copied from DNA that tell the cell which amino acids to assemble.

2. Ribosome: The cellular machine made of proteins and ribosomal RNA that locks onto the mRNA and builds the protein.

3. tRNA (Transfer RNA): Small molecules that carry specific amino acids and match them to the mRNA code.

4. Codon: A group of three mRNA nucleotides that codes for one specific amino acid or a stop signal

Anticodon

Base triplet that each tRNA bears

What is tRNA

a small RNA molecule that links genetic code to the building blocks of proteins during cell translation

What is the initiation stage of translation

Starts when the small ribosomal subunit binds to mRNA and a special initiator

Initiator tRNA carries the amino acid methionine

Small subunit moves along the mRNA until it reaches the start codon (AUG)

What is the elongation stage of translation

Translation proceeds along the mRNA in a 5’—>3’ direction

Ribosome and mRNA move relative to each other, codon by codon

During translation, what happens as mRNA moves one codon at a time relative to the ribosome

a tRNA with a complementary anticodon pairs with each codon, adding its amino acid to the growing polypeptide chain

How long does elongation continue on for

Until a stop codon reaches the ribosome’s A site

How are codons read

As nucleotides in groups of three, in the 5’ to 3’ direction

What is the start codon of translation

AUG

It codes for the amino acid methionine (MET) in eukaryotes

What can mutations affect

Protein structure and function