Bio semesterr review paper

How are enzymes affected by temperature, pH, concentration of the enzyme?

it works best at an optimal pH and temperature and usually increases with more enzyme if there’s enough substrate, but extreme pH or temperatures reduce activity.

What would be the expected result of reusing an enzyme again in an experiment?

Reusing an enzyme should still produce the same reaction because enzymes are not used up.

what causes enzyme denaturing and how does it affect enzyme activity?

enzymes denature when exposed to extreme heat, pH, or chemicals, which changes their shape and stops them from working properly.

Miller–Urey Experiment

• Purpose: To test whether organic molecules needed for life could form under early Earth conditions.

• Reactants: Water (H₂O), methane (CH₄), ammonia (NH₃), hydrogen (H₂), and electricity (lightning).

• Products: Amino acids and other simple organic molecules.

Nucleic acids

: Store and transmit genetic information (DNA, RNA). CHONP

Proteins:

Build structures and act as enzymes to speed up chemical reactions. CHON

Lipids:

Store long-term energy and make up cell membranes. CHO

Carbohydrates

• Simple sugars: Quick energy (e.g., glucose).

• Starches: Energy storage for later use.

• C1H2O1

Why are eukaryotic cells more complex than prokaryotes?

Because they have a nucleus and membrane-bound organelles that allow specialized functions and greater organization.

Nucleus

Stores DNA and controls cell activities

Mitochondria

Produces energy (ATP) through cellular respiration.

Chloroplast

: Makes glucose using photosynthesis (plants only).

Ribosome:

Builds proteins.

Vacuole:

Stores water, nutrients, and wastes.

Lysosome

: Breaks down waste and old cell parts.

Golgi apparatus:

Modifies, packages, and ships proteins and lipids.

Smooth Endoplasmic Reticulum

Produces lipids and detoxifies chemicals.

Rough Endoplasmic Reticulum

Produces and folds proteins (has ribosomes).

Which organelles produce new molecules?

Ribosomes, mitochondria, chloroplasts, smooth ER, and rough ER.

Interphase

Cell grows, carries out normal functions, and prepares to divide

G1 phase

: Cell grows and makes proteins and organelles.

S phase

DNA is replicated (copied).

G2 phase

: Cell grows more and prepares for mitosis.

Mitosis

: Nucleus divides and chromosomes are separated.

Cytokinesis:

Cytoplasm divides, forming two identical daughter cells.

Purposes of Mitosis

• Growth

• Repair

• Replacement of damaged or worn-out cells

What does a cancer/tumor look like at the cellular/tissue level?

appear crowded, irregular in shape, and disorganized, dividing uncontrollably to form a mass (tumor) that disrupts normal tissue structure.

How does the disruption of the cell cycle cause cancer?

when cell-cycle checkpoints fail to stop damaged cells, allowing them to pass through mitosis repeatedly and divide uncontrollably instead of being repaired or destroyed.

How do specialized cells express different genes even though they all have the same DNA?

only certain genes are turned on or off in each cell, even though all cells contain the same DNA.

How do environmental factors influence which genes are expressed?

factors like temperature, chemicals, nutrients, and signals from other cells can turn genes on or off by affecting how DNA is read.

How does the position of cells within an embryo affect their development?

exposes it to different chemical signals, causing it to develop into a specific cell type.

What happens during crossing over?

Homologous chromosomes exchange segments of DNA during meiosis.

Why is it the origin of variation in offspring?

It creates new combinations of genes that were not present before.

Why are siblings different?

Each gamete gets a unique mix of genes due to crossing over and meiosis.

Are gametes diploid or haploid? Why?

Gametes are haploid because they contain one set of chromosomes, so chromosome number stays constant after fertilization.

Are zygotes diploid or haploid? Why?

Zygotes are diploid because they form when two haploid gametes combine, restoring two sets of chromosomes.

What did Watson and Crick discover? Draw an example.

Discovered the double-helix structure of DNA.
Sugar-phosphate backbone
║ A—T ║
║ C—G ║
║ A—T ║

What is Chargaff's rule and ratios?

amount of adenine equals thymine (A = T) and the amount of cytosine equals guanine (C = G), so their ratios are 1:1.

Structure of DNA: Parts of a nucleotide

• Phosphate group

• Deoxyribose sugar

• Nitrogenous base

What happens during DNA Replication?

copies DNA by unzipping the double helix and using each strand as a template to build a new complementary strand.

What forms the backbone of a strand of DNA?

Sugar (deoxyribose) and phosphate

What is the main enzyme used in Transcription and what does it do?

RNA polymerase, which builds an RNA strand by copying DNA.

mRNA (messenger RNA):

Carries genetic instructions from DNA to the ribosome.

tRNA (transfer RNA):

Brings amino acids to the ribosome during protein synthesis.

rRNA (ribosomal RNA):

Makes up the ribosome, where proteins are assembled.

How can a mutation result in no change of amino acid?

Because multiple codons can code for the same amino acid (a silent mutation).

In what order are the 3 types of RNA used in Translation?

mRNA → tRNA → rRNA

The greatest variation comes from mutations of genes in what type of cells?

gametes (sex cells)

Point mutations

substitution, insertion, deletion

what is a frameshift mutation?

A mutation caused by an insertion or deletion that shifts the reading frame of the gene.

what type of mutation has the greatest effect?

Frameshift mutations (deletions & insertions)

Where would a mutation have the greatest effect, at the beginning, middle, or end of a gene sequence?

beginning

Dominant

: Trait that masks another trait

Recessive

Trait expressed only when no dominant allele is present

Homozygous:

Two identical alleles

Heterozygous

Two different alleles

Codominance

Both alleles are fully expressed (roan cattle with red and white patches)

Multiple alleles

: More than two alleles exist for a trait in a population

Incomplete dominance

a blended phenotype (e.g., pink flowers from red & white)

What do Punnett squares determine?

the possible genotypes and phenotypes of offspring.

How can a dihybrid cross showing only the phenotypes of offspring be used to determine the genotypes of the parents?

By using the phenotypic ratios of offspring, you can work backward to identify whether parents are homozygous or heterozygous for each trait.

if parents who are both heterozygous for 2 traits are crossed, and they have 64 offspring, how many of the offspring would you expect to have both recessive traits?

Phenotypic ratio = 9:3:3:1

What are the possible blood types and their genotypes?

• A: IAIA or IAi

• B: IBIB or IBi

• AB: IAIB

• O: ii

How can you determine the genotypes of fur color in rabbits with multiple alleles from their phenotypes?

you determine genotypes by comparing phenotypes to the dominance hierarchy of alleles (most dominant allele present determines fur color).

How can you determine if a pedigree depicts sex-linked trait or autosomal trait?

• Sex-linked trait: More common in males; passed from mother to son

• Autosomal trait: Affects males and females equally