bio 1 final exam irsc

3 requirements for natural selection

inheritance of traits, variation, and variation in characteristics (reproductive advantage)

A change in the allele frequency of a population as a result of chance events rather than natural selection- important in small populations (bottleneck and founder effect)

genetic drift

tested and confirmed explanation of observations or phenomena

scientific theory

what happens during crossover?

happens during Prophase 1 of meiosis, when homologous chromosomes pair up and exchange genetic material at points called chiasmata. leads to genetic recombination, increasing variation in gametes

Differences between Active transport and Passive transport

passive transport requires no energy and moves substances down their concentration gradient. active transport requires ATP and moves substances against their concentration gradient

DNA structure

double helix built out of nucleotides.

nucleotides have 3 parts, phosphate group, deoxyribose sugar and 4 nitrogenous bases (A, T , C, G).

bases are connected by hydrogen bonds.

antiparallel strands 5'-3' and 3'-5'

DNA located in nucleus of eukaryotic cells

monomers and polymers

carbohydrates-monosaccharides

proteins- amino acids

nucleic acids-nucleotides

lipids-glycerol and fatty acids

Meiosis 1

Homologous chromosomes separate

prophase 1 - pair up and crossing over

metaphase 1- pairs align randomly at metaphase plate

anaphase 1- chromosomes pulled to opposite poles. sister chromatids stay together

telophase 1 and cytokinesis- 2 haploid cells form. each chromosome still has 2 sister chromatids

Meiosis 2

sister chromatids separate

prophase 2- spindles reform in both haploid cells

metaphase 2- chromosomes align at the center

anaphase 2- sister chromatids pulled apart

telophase 2 and cytokinesis- 4 genetically unique haploid daughter cells result and each contains a set of chromosomes

stores DNA and controls cells activities

nucleus

make proteins

ribosomes

synthesizes proteins (covered in ribosomes)

rough endoplasmic reticulum

Synthesizes lipids and detoxifies chemicals

smooth ER

Modifies, sorts, and packages proteins/lipids for transport ("post office")

golgi apparatus

Produces ATP through cellular respiration ("powerhouse")

mitochondria

Perform photosynthesis (convert sunlight to glucose)

chloroplasts (plants only)

Break down waste, damaged organelles, and pathogens ("cleanup crew")

lysosomes

Break down fatty acids and toxins

peroxisomes

Stores water, nutrients, and waste (large in plants)

vacuole

Gives shape, support, and helps with movement (made of microtubules, etc.)

cytoskeleton

controls what enters/exits the cell; maintains homeostasis

cell membrane

Provides structure and protection outside the membrane

cell wall (plants only)

Help organize cell division (part of centrosome)

centrioles ( animal cells)

transcription

process of making an RNA copy of a gene's DNA sequence.

starts with DNA in nucleus and ends with mRNA.

key molecules involved -DNA, RNA polymerase, RNA nucleotides

translation

second step of gene expression, where the mRNA made during transcription is used to build a protein.

starts with mRNA in cytoplasm and ends with protein.

key molecules involved -mRNA, ribosome, tRNA, amino acids

isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

3 parts of nucleotide

phosphate group, 5 carbon sugar, nitrogenous base

binary fission

how bacteria (prokaryote) divide

1- singular circular DNA chromosome copies itself

2-bacterium gets larger as prepares to divide

3-2 DNA copies move to opposite sides of cell

4-cytokinesis (cell membrane pinches inward, dividing cytoplasm)

5- 2 genetically identical daughter cells result

what is made/ released during photosynthesis?

glucose is made and oxygen is released as a byproduct.

ATP ( temporary energy source) and NADPH (provides electrons for glucose production) are intermediate molecules

codon

found in mRNA and specifies the amino acid

anticodon

found on tRNA and matches codon + delivers right amino acid during translation

codons and anticodons interaction

1-Ribosome reads the mRNA codon

2-A tRNA with the complementary anticodon binds to the codon

3-The tRNA carries the correct amino acid

4-The amino acid is added to the growing polypeptide chain

endosymbiosis theory

proposes that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by a host cell and evolved into organelles.

peppered moth story

Before Industrial Revolution:

-Light-colored moths blended into clean, lichen-covered trees

-Dark moths were rare (eaten more often)

After Industrial Revolution:

-Trees darkened from soot

-Dark moths were camouflaged

-Light moths were eaten more

Result:

-Dark moths became more common

-Shows natural selection based on environmental change

rubisco

Most important enzyme in photosynthesis.

Catalyzes carbon fixation in the Calvin cycle (adds CO₂ to RuBP).

Found in chloroplasts.

ATP synthase

Makes ATP during the light-dependent reactions

Uses energy from the proton gradient (chemiosmosis)

NADP⁺ Reductase

Final step in light reactions

Transfers electrons to NADP⁺ → forms NADPH (used in Calvin cycle)

the process of converting inorganic CO₂ into organic molecules (like sugars) during photosynthesis. occurs in Calvin Cycle + catalyzed by rubisco

carbon fixation

eukaryote

nucleus, DNA is linear, has membrane bound organelles

ex: plants, fungi, animals, protists

prokaryote

no nucleus, DNA is circular in cytoplasm, no membrane bound organelles, smaller size

ex: bacteria, archaea

directional selection

Definition: Favors one extreme trait

Bell curve: Shifts left or right

Example: Dark-colored moths become more common after pollution

stabilizing selection

Definition: Favors the average trait, not extremes

Bell curve: Narrows around the middle

Example: Human birth weight — too low or too high is risky

disruptive selection

Definition: Favors both extremes, not the average

Bell curve: Splits into two peaks

Example: Birds with small or large beaks survive better than medium

increases H+ concentration

ph< 7

acid

increases OH- concentration

ph>7

base

how atomic mass is determined

The weight of an atom is called its atomic mass (or atomic weight), and it is determined by: Protons and Neutrons

Electrons are so small they barely contribute to mass

atomic number

number of protons in nucleus of atom

A pair of chromosomes — one from each parent — that are similar in size, shape, and gene content.

They carry the same genes, but possibly different versions (alleles).

homologous chromosome

Body parts in different species that have a similar structure and shared evolutionary origin, even if their functions differ.

homologous structures

It stores and transports energy for nearly all cellular processes

Energy is released when one of its phosphate bonds is broken (→ becomes ADP)

ATP (adenosine triphosphate)

1 division, 2 cells produced, no chromosome number change, makes body cells (somatic)

purpose: growth, repair, and asexual reproduction

mitosis

2 divisions, 4 cells produced, chromosome number changed by half, makes sex cells (gametes)

purpose: produce gametes (sperm or egg) for sexual reproduction

how does a enzyme catalyst affect a reaction?

lowers activation energy by reducing the amount of energy needed to start the reaction, so reaction is faster and more efficient.

increases reaction rate by lowering activation energy enzymes allow more reactions to occur in less time, so rxn completion is faster than it would be without the enzyme catalyst.

Forms of active transport (require energy), Types of endocytosis, Involve the cell membrane folding in to form vesicles. cell eating, large particles taken in, large vesicle, common white blood cells, and purpose is to defense, remove invaders and eat solids

phagocytosis

Forms of active transport (require energy), Types of endocytosis, Involve the cell membrane folding in to form vesicles. cell drinking, fluids + small dissolved molecules take in, small vesicle, most cells are common, and the purpose is to absorb nutrients, sample surroundings

pinocytosis

Parts of the Cell Cycle

Interphase (G1, S, and G2), Mitosis, Cytokinesis

triglyceride structure + function

glycerol + 3 fatty acids

energy storage

phospholipid structure + function

glycerol + 2 fatty acids + phosphate group

forms cell membranes

light-dependent reactions + where

part of photosynthesis that absorbs energy from sunlight and transfers energy into chemical energy.

happens in thylakoid membrane of a chlorplast (plant cell)

light independent reactions

set of reactions in photosynthesis that do not require light; energy from ATP and NADPH is used to fix CO2 into glucose.

happens in stroma of chloroplast (fluid-filled space outside thylakoid)

where is most ATP made?

cellular respiration- electron transport chain in inner mitochondrial membrane

Enzymes Truth

nondisjunction

Error in meiosis in which homologous chromosomes fail to separate. leads to aneuploidy

aneuploidy

Abnormal number of chromosomes.

homozygous

An organism that has two identical alleles for a trait

heterozygous

An organism that has two different alleles for a trait

hemizygous

only one copy of a gene

dominant

allele that masks the other; expressed if present

recessive

only expressed if both alleles are recessive

genotype

genetic makeup of an individual

phenotype

the physical trait expressed

allele

a version of a gene

nature of the cell membrane

Has a hydrophobic head (phosphoric acid-glycerol) and hydrophilic tail (two fatty acid chains-one kinked).

"fluid mosiac model"

the central dogma

genetic information flows in living organisms:

DNA stores it

RNA carries it

Proteins express it

exergonic

Releases energy (e.g., cellular respiration)

Products have less free energy than reactants

negative ΔG

endergonic

Requires energy input (e.g., photosynthesis)

Products have more free energy than reactants

positive ΔG

activation energy

the minimum amount of energy required to start a chemical reaction

free energy

energy that is available to do work

reactants

elements or compounds that enter into a chemical reaction

products

The elements or compounds produced by a chemical reaction.

anabolism

builds molecules

catabolism

breaks molecules down

cell to cell junctions

tight junction, desmosomes, gap junctions, and plasmodesmata

stages of mitosis

prophase, prometaphase, metaphase, anaphase, telophase

prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms

Prometaphase (Mitosis)

The nuclear membrane disintegrates. Spindle microtubules attach to chromatids.

metaphase

Chromosomes line up in the middle of the cell

anaphase

sister chromatids are pulled apart

telophase

2 nuclei form, chromosomes decondense

cytokinesis

division of the cytoplasm to form two separate daughter cells

major polysaccharides

starch, glycogen, cellulose, and chitin

starch

long chains of glucose branched and unbranched in plant cells their function is energy storage in plants

glycogen

Highly branched chains of α-glucose in animal cells

their function is short term energy storage in animals

cellulose

Straight, rigid chains of β-glucose in plant cells.

its function is structural support in plant cell walls

chitin

Chains of β-glucose + nitrogen-containing side groups in fungi and arthropods

its function is structural- forms of exoskeletons and fungal cell walls

hierarchy of organization for living cells

atom, molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere

hydrophobic

"Water-fearing" — does not dissolve in water

hydrophillic

"Water-loving" — dissolves easily in water

sodium potassium pump

a carrier protein that uses/requires ATP to actively transport 3 sodium ions out of a cell and 2 potassium ions into the cell.

Maintains electrochemical gradient

Found in animal cells, crucial for nerve and muscle function

photosynthesis

in chloroplasts (plants). converts light to glucose