2 st part of first molec exam

Prokaryotes

Circular + Nucleoid

Eukaryote

Linear + Nucleus

How many chromosomes are present in a bacterium/archaeon?

one single chromosome

What is a nucleoid?

The region of a prokaryotic cell where its DNA is located.

What are nucleoid associated proteins?

Small, basic proteins in prokaryotes that bind DNA to assist in folding/organize the bacterial DNA

what the architecture of nucleoid associated protein?

DNA is compacted into loops

Eukaryotes Nucleus function

DNA is stored inside the nucleus.

Eukaryote; Chromatin function

DNA and packaged proteins

Eukaryote Nucleosomes function:

DNA is wrapped around histone proteins

Eukaryote Core Histones:

H2A, H2B, H3, and H4

Eukaryote: Heterochromatin

Tightly condensed, transcriptionally inactive (non-coding), and AT-rich. It stains darker with Giemsa staining. Includes regions like centromeres and telomeres.

Eukaryote: Euchromatin

Loosely packaged, transcriptionally active (coding), and GC-rich. It stains lighter with Giemsa staining.

What can be determined from a karyotype

The number, size, and shape of chromosomes and whether there are major chromosomal abnormalities.

What are human autosomes?

The non-sex chromosomes (chromosomes 1–22).

How many do humans have?

44 autosomes = 22 pairs

What do autosomes encode?

They contain genes that provide instructions for many traits and biological functions.

How are autosomes paired?

as homologous chromosomes, one chromosome comes from each parent.

What are sister chromatids?

Identical, replicated copies of a single chromosome held together at the centromere

What are non-sister chromatids?

Chromatids belonging to different chromosomes of a homologous pair (one maternal, one paternal).

What is Giemsa staining?

A staining technique used to produce the characteristic bands on chromosomes.

What are chromosomal banding patterns?

Dark and Light bands that appear on chromosomes when they are stained. They help identify and distinguish chromosomes.

What do the dark bands indicate?

AT-rich, tightly packed, gene-poor Heterochromatin

What do the light bands indicate?

GC-rich, loosely packaged, gene-rich Euchromatin.

What sequences are present at centromeres?

Repetitive, double-stranded, satellite heterochromatin sequences

What is the purpose of the centromere?

Specialized chromosomal regions that bind sister chromatids together and assemble the kinetochore

What is a mitotic spindle?

is a structure made of microtubules that moves and separates chromosomes during cell division.

What are the parts of a spindle?

Microtubules

Kinetochore microtubules

kinetochore

Astral microtubules

What organism(s) contain polytene chromosomes?

Notably present in the salivary gland cells of Drosophila (fruit flies).

What is the purpose of polytene chromosomes?

They provide massive gene copies to facilitate extremely high-volume transcription and protein production

Eukaryote Mitochondrial genome

smaller, usually circular, and has fewer genes. Exclusively maternally inherence

Eukaryote Nuclear genome

larger, linear chromosomes, and has many more genes and Mendelian

What genes are encoded by mitochondrial ?

The human mitochondrial genome encodes 37 genes

How many copies of the genome per mitochondria?

Multiple copies, often 2–10 copies per mitochondrion

What is heteroplasmy?

The presence of more than one type of mitochondrial DNA within a single cell or individual, such as a mixture of normal and mutated mtDNA.

What is contained in DNA?

both coding DNA and noncoding DNA.

What are the feature of coding DNA? Sequence composition

Exons

What are the feature of non-coding DNA? Sequence composition

Introns, repetitive elements, regulatory sequences, IncRNAs

Why is noncoding DNA important?

it can regulate gene expression

Locus (plural loci) definition

The location of a specific pairs of gene

Allele definition

Alternative version of the same gene pair

What are DNA polymorphisms?

are variations in DNA sequences that exist among individuals

Where are repeated DNA regions generally found?

Noncoding DNA

What is a haplotype?

A specific group or set of DNA variations (such as SNPs) that reside close together on the same chromosome and are typically inherited together as a single block from a parent.

RFLPs (Restriction Fragment Length Polymorphisms)

Variations in the lengths of DNA fragments produced when DNA is cut by restriction enzymes.

Non coding: Used in classic DNA fingerprinting.

STRs (Short Tandem Repeats) Polymorphisms

Variable-length blocks of short repeating sequences (2-6 bp) in noncoding regions used for forensic 'DNA Typing

SNPs (Single Nucleotide Polymorphisms):

Single base-pair substitutions found in both coding and noncoding regions.

What are Transposons

DNA sequences that can move from one location in the genome to another. They are divided into DNA transposons and retrotransposons (LINEs and SINEs).

SINEs

Short Interspersed Nuclear Elements

Alu Element

A 300-nucleotide SINE that represents the most abundant transposon in the human

Coding feature mutation effects?

A mutation can change the protein that is produced, potentially affecting its function.

Non Coding mutation effect

can affect gene regulation/chromosomal structure and other process.

Mutation effect: Point Mutation?

Silent- Nonsense-Missence

Mutation Effects: Frameshift mutations

Caused by an insertion or deletion of nucleotides that is not a multiple of 3.

What are the four major classes of Chromosomal Abnormalities?

Deletion: Removes a chromosomal segment.

Duplication: Repeats a segment.

Inversion: Reverses a segment within the chromosome.

Translocation: Moves a segment to another, non-homologous chromosome.