Biology Midterm 3 part 1 Flashcards
Name some cell types and relate their overall shape and internal structure to their special
functions
Red blood cells (erythrocytes):
Disc-shaped with a biconcave center, allowing for maximum surface area to carry oxygen efficiently, lacking a nucleus to maximize space for hemoglobin protein which binds to oxygen.
Nerve cells (neurons):
Long, thin, elongated with multiple branching dendrites and a single long axon, facilitating rapid transmission of electrical impulses over long distances.
Muscle cells (myocytes):
Elongated and cylindrical with organized bundles of contractile proteins (actin and myosin) that enable muscle contraction.
Identify on a cell model or diagram the three major cell regions (nucleus, cytoplasm, and
plasma membrane)
On a cell diagram, the nucleus would be the large, centrally located oval structure surrounded by a double membrane, the cytoplasm would be the jelly-like substance filling the space between the nucleus and the outer cell boundary, and the plasma membrane would be the thin outer layer that encloses the entire cell, clearly separating the cell’s internal components from the external environment
Identify the organelles on a cell model or describe them and indicate the major function of
each.
see google
Describe the structure and function of the cell nucleus and its contents
The cell nucleus is a membrane-bound organelle that acts as the control center of the cell, housing the cell’s genetic material (DNA) in the form of chromosomes, and is responsible for regulating gene expression, DNA replication, and ribosome biogenesis; it is surrounded by a double membrane called the nuclear envelope, which contains nuclear pores allowing for the movement of molecules between the nucleus and cytoplasm, and includes a dense region called the nucleolus where ribosomes are assembled
Describe where and how DNA is stored within the cell
In a eukaryotic cell, DNA is primarily stored within the nucleus, a membrane-bound organelle located in the cell’s center, where it is organized into structures called chromosomes; this DNA is often referred to as “nuclear DNA”. To fit within the nucleus, the long strands of DNA are tightly coiled around proteins called histones, forming a compact structure
Identify the structure and molecular make up of DNA
DNA, or deoxyribonucleic acid, is structured as a double helix, consisting of two long strands of nucleotides twisted around each other, where each strand is made up of alternating sugar (deoxyribose) and phosphate groups forming the backbone, with nitrogenous bases (adenine (A), thymine (T), cytosine (C), and guanine (G)) projecting inwards to pair with complementary bases on the opposite strand, held together by hydrogen bonds
List the similarities and differences between the various nucleic acid molecules
Nucleic acid molecules, primarily DNA and RNA, share the basic building block of a nucleotide containing a phosphate group, a sugar, and a nitrogenous base; however, their key difference lies in the type of sugar (deoxyribose in DNA and ribose in RNA), with DNA being double-stranded and RNA being single-stranded, and DNA using thymine (T) as a base while RNA uses uracil (U) instead; both molecules use adenine (A), cytosine (C), and guanine (G) as bases, with specific base pairing rules (A-T/U and C-G)
Summarize how DNA is replicated in a semi-conservative way
DNA replicates in a semi-conservative manner, meaning that when a new DNA molecule is formed, one strand comes from the original DNA molecule and the other strand is newly synthesized, resulting in two daughter DNA molecules, each containing one “old” strand and one “new” strand, acting as a template for the new complementary strand to be built upon; essentially, each original DNA strand serves as a blueprint for creating a new complementary strand, preserving half of the original DNA in each new molecule
Explain how errors in replication can lead to mutations
Errors in DNA replication can lead to mutations when a mistake is made during the copying process, resulting in an incorrect nucleotide being incorporated into the new DNA strand, and if this error is not corrected by the cell’s repair mechanisms, it becomes a permanent change in the genetic sequence, which is considered a mutation; essentially, the incorrect base pair is then used as a template for further replication, perpetuating the change in the DNA sequence across subsequent cell divisions.
Investigate how differences in DNA sequences can be used in DNA profiling
DNA profiling utilizes the small variations in DNA sequences between individuals, particularly in regions with repetitive DNA sequences called “short tandem repeats” (STRs), to create a unique genetic profile for each person, allowing for identification and comparison between different DNA samples, commonly used in forensic investigations and paternity testing
Examine how the structure of DNA fits in the central dogma
The structure of DNA perfectly aligns with the central dogma of molecular biology by providing a stable, double-stranded molecule with a specific sequence of nucleotide bases that can be “read” to generate RNA during transcription, which then serves as the template for protein synthesis during translation, effectively translating the genetic code stored in DNA into functional proteins.
Identify and describe the unique function of the organelles involved in protein synthesis.
The primary organelle responsible for protein synthesis is the ribosome; it acts as the site where amino acids are assembled into polypeptide chains based on the instructions provided by messenger RNA (mRNA), essentially “building” the protein molecule; ribosomes can be found free in the cytoplasm or attached to the rough endoplasmic reticulum (RER)
Describe the process of protein synthesis, including how the genetic information is transferred during transcription and translation.
Protein synthesis is the cellular process of creating proteins, which occurs in two key steps: transcription, where genetic information is transferred from DNA to messenger RNA (mRNA), and translation, where the mRNA sequence is read to assemble amino acids into a polypeptide chain, forming a protein; essentially, the DNA code is “transcribed” into RNA, which is then “translated” into a protein sequence.
