TEAS exam prep science part 1

Biological systems are organized hierarchically:

cells → tissues → organs → organ systems → organisms

Cells are the fundamental _______

unit of life,

Cells contain smaller structures called _______

organelles

what are the two main types of cells?

prokaryotic (no nucleus, no membrane-bound organelles) and eukaryotic (have nucleus and membrane-bound organelles)

what does the cell membrane (plasma membrane) control?

selective permeability, maintaining homeostasis

whats cytoplasm?

a jellylike substance supporting organelles inside the cell

whats the cytoskeleton?

provides structural support and aids in cell movement

what do ribosomes do?

synthesize proteins also found in both prokaryotic and eukaryotic cells

what is the nucleus?

the control center in eukaryotic cells, housing DNA and nucleolus (site of ribosome assembly)

Endoplasmic reticulum (ER) ________ molecules

processes and transports

rough ER has ________

ribosomes and produces proteins

smooth ER lacks _______ nd is involved in lipid synthesis and detoxification

ribosomes

what is the Golgi apparatus?

it modifies, sorts, and packages proteins and lipids for transport or secretion

Mitochondria generate ATP energy through _______

cellular respiration, using glucose and oxygen also known as the "powerhouse" of the cell

What is the purpose of chloroplast in plant cells?

perform photosynthesis, producing glucose using sunlight

lysosomes digest ______

cellular waste and foreign invaders

vacuoles _________

store nutrients, waste, and maintain cell pressure (especially in plants)

how do cells form?

only from pre-existing cells, emphasizing replication

cell

Basic unit of life in all organisms

Organelle

specialized structures within cells performing specific functions

Prokaryote

Cell without a nucleus or membrane-bound organelles (e.g., bacteria)

Eukaryote

Cell with a nucleus and membrane-bound organelles (e.g., plants, animals)

Plasma membrane

Selectively permeable barrier controlling substance movement in and out of the cell

Cytoplasm

Gel-like substance inside the cell holding organelles

Cytoskeleton

Network of fibers providing structure and movement to the cell

Ribosomes

site of protein synthesis

Nucleus

Control center of the cell

Nucleolus

Found inside the nucleus and produces ribosomes

Endoplasmic Reticulum (ER)

Membrane system for protein and lipid synthesis and transport

Rough ER

studded with ribosomes, involved in protein synthesis

Smooth ER

no ribosomes and makes lipids

Golgi apparatus

modifies, sorts, and packages proteins and lipids

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

ATP

adenosine triphosphate, main energy currency of the cell

Chloroplast

Site of photosynthesis

Lysosomes

containing enzymes to digest cellular waste and invaders

Vacuole

Fluid-filled sac for storage and maintaining pressure

Homeostasis

Stable internal environment maintained by the cell

Prokaryotic cells lack ________

nucleus and membrane-bound organelles

bacteria is ______

unicellular prokaryotes

humans are _____

multicellular eukaryotes

Eukaryotic cells have ______

nucleus and membrane bound organelles

What does mitosis produce?

two identical daughter cells

What does meiosis produce?

haploid gametes

What type of cell do both mitosis and meiosis start from?

diploid (2N) cell

What are the stages of both mitosis and meiosis?

Prophase, Metaphase, Anaphase, Telophase (meiosis repeats these stages twice)

What separates in mitosis vs. meiosis I?

Mitosis: sister chromatids separate

Meiosis I: homologous chromosomes separate

During which phase does crossing over occur?

Prophase I of meiosis

What is the result of crossing over?

genetic diversity

How many chromosomes do humans have?

46 total (23 pairs)

How many chromosomes are in gametes?

23

What happens during interphase?

chromosomes replicate, but chromatids stay joined at the centromere

What are the outcomes of mitosis and meiosis?

Mitosis: 2 identical diploid cells Meiosis: 4 unique haploid cells.

Where do homologous chromosomes pair?

In prophase I of meiosis

How do chromosomes line up in metaphase for mitosis vs. meiosis I?

Mitosis: singly Meiosis I: in pairs

What enzyme starts transcription in protein synthesis?

RNA polymerase

What is mitosis?

Cell division producing two identical diploid body cells

What is meiosis?

Cell division producing four genetically diverse haploid gametes

diploid (2N)

2 sets of chromosomes

haploid (N)

one set of chromosomes, typical of gametes

What is a chromatid?

half of a duplicated chromosome

What is a centromere?

The region where sister chromatids are joined

What are homologous chromosomes?

Chromosome pairs (one from each parent) similar in size and gene location.

What is crossing over

Exchange of genetic material between homologous chromosomes during meiosis

What are gametes?

sex cells (sperm and egg)

What is DNA?

deoxyribonucleic acid, genetic DNA

What is the structure of DNA?

Double helix made of nucleotides with sugar-phosphate backbone

What are the DNA base pairing rules?

A - T, C-G

What is a gene?

segment of DNA that codes for a protein

What is gene regulation?

Mechanisms that control when and how genes are expressed

How is DNA packaged?

It wraps around histone proteins to form chromosomes

What is RNA?

Ribonucleic acid, used to decode DNA instructions for protein synthesis

What are the three types of RNA?

mRNA, tRNA, rRNA

What are codons and anticodons?

Codons: 3-base mRNA sequences Anticodons: complementary 3-base tRNA sequences

What base does RNA use instead of thymine (T)?

Uracil (U)

Where is RNA found?

nucleus and cytoplasm

What happens during transcription?

DNA is converted to mRNA in the nucleus

What happens during translation?

The ribosome uses mRNA and tRNA to assemble amino acids into proteins

What is the sequence of protein synthesis?

DNA -> RNA -> Protein

What do stop codons do?

Signal the end of protein synthesis

whats the RNA pairing?

A-U

What happens when sperm and egg fuse?

form a diploid zygote

What is the role of meiosis in heredity?

Creates genetic variation through crossing over and random assortment

PAT in cell divison phase=

Prophase, Anaphase, Telophase