细胞生命起源：基于机械设计与分子化石的理论探讨

需积分: 5 85 浏览量更新于2024-08-07 收藏 141KB PDF 举报

本文《细胞生命的起源》由Donald E. Ingber撰写，探讨了生物架构与微观力学设计在理解生命起源中的关键作用。作者提出，现今细胞的构造原则——如 tensegrity（张力-结构）架构，以及能量最小化、拓扑约束、结构层次、自我催化集合和固态生物化学等基本设计原理，在早期生命的进化过程中同样起着指导作用。他强调，细胞通过tensegrity稳定自身，这种机制不仅体现在现代细胞的结构中，而且是过去生命形式存在的活化石记录。 Ingber的核心观点是，从细胞如何通过机械稳定性构建复杂的微结构，可以追溯到最早的细胞形态形成过程。生物体的自组装并非随机发生，而是遵循一套规则，这些规则随着时间推移逐渐复杂化，直至产生了具备自我复制能力的生物体，即原始细胞。这一理论建立在对细胞内部结构的深入分析之上，尤其是对于那些支持固相生物化学活动的分子支架的研究。作者认为，通过考察生物体如何在不同尺度上进行层次化的自我组装，可以从微结构水平上解释生命的起源和发展。从原子和分子级别的元素逐渐组合成具有功能性的多层次结构，这个过程是有序且有目的的，最终导致了生命的诞生。这种物理基础为理解生命如何从无生命物质中逐步演化而来提供了强有力的支撑。《细胞生命的起源》论文通过对生物力学和细胞设计的深入剖析，揭示了生命起源时的关键物理原则，并将其与现代细胞的特征联系起来，提出了一个新颖而富有洞察力的生命起源理论框架。这个理论挑战了传统的观念，为我们理解生命起源提供了新的视角。

bearing materials in these regions (e.g., triangular supports in

corners of rectangular picture frames). A more efficient way to

stabilize a rigid framework is through triangulation such that

each strut is oriented so as to constrain the joint to a fixed

position. For these reasons, Nature repeatedly selected out

geodesic tensegrity systems. A more elegant and economical

solution to this problem that results in both structural efficiency

and flexibility is to impose an internal tension (prestress) to

reduce the play in the joints. Hence, Nature soon discovered

prestressed tensegrity structures as well (Table 1).

In summary, because it is the most economical solution to

the design challenges created by spatial constraints, energy

minimization rules, and the need to efficiently balance forces,

tensegrity is the way Nature builds. It is the only building

principle that can provide a single explanation (Occam's razor)

for how both unicellular organisms with geodesic exoskeletons

(e.g., radiolaria) and huge behemoths with prestressed

musculoskeletons (e.g., dinosaurs) could ever come into

existence.

Autocatalytic sets and solid-state biochemistry

Another concept that may be relevant to how life originated is

the idea is that once structures come about that can mediate

catalysis, then coherent self-reinforcing webs of chemical

reactions or ``autocatalytic sets'' will spontaneously em-

erge.

(18)

For example, if a primitive catalyst (protoenzyme) 1

accelerated the formation of protoenzyme 2 and 2 accelerated

the formation of 3, and so on, then at some point protoenzyme

X would emerge that could catalyze formation of protoenzyme

1. Loop closure would result in self-reinforcement of this

particular web of interactions. Thus, this particular cluster of

interacting components would increase in abundance relative

to molecules that were excluded from the web (Table 1).

On one hand, if autocatalytic sets were to form in solution

(as commonly assumed), then huge numbers of reactions may

be required before self-organization would be observed. On

the other hand, if some of these primitive protoenzymes

catalyzed the assembly of 3D scaffolds that bound the

interacting molecules and brought them in close proximity,

then the likelihood that the product of one reaction could

function as a substrate for a neighboring enzyme would

increase dramatically. Incorporation of this form of solid-phase

or ``solid-state'' biochemistry would therefore greatly increase

the probability that an autocatalytic set would develop and be

sustained over time (Table 1).

In fact, one of the major limitations of past theories of the

origin of life is that they failed to consider the importance of

solid-state biochemistry. The cytoskeleton of eukaryotic cells

orients most of the cell's organelles and many of the enzymes

and substrates that make up its metabolic machinery.

(14,19,20)

This increases the efficiency of chemical reactions because

substrate availability is not diffusion-limited in this context and

much larger molecules that would normally be insoluble or

spatially restricted by diffusion may be funneled into complex

metabolic pathways.

(21)

It also provides a mechanism to

integrate structure and function such that cells can respond

directly to environmental stresses (and scaffold deformation)

by altering cellular biochemistry

(22±24)

and strengthening

the scaffold against disruption.

(3)

Importantly, prokaryotic

cells also appear to use solid-state biochemistry on primitive

Table 1. Natural design principles

* Minimize energy expenditure. Nature is most economical and, thus, all natural structures tend to minimize energy and mass.

* Obey spatial constraints. Certain topologial rules constrain the possible forms that matter can take on, regardless of size or position.

* Develop emergent properties through architecture. At every size scale, complex properties and functions emerge from the behavior of the

ensemble; the material properties of any single element is much less important than how the different elements are joined and positioned in 3D.

* Establish a mechanical equilibrium. Architectural stability requires the establishment of a global balance of mechanical forces, although local

regions may be stressed.

* Use discrete networks. Nature does not use bulk solids to build; discrete porous networks offer greater structural efficiency and versatility.

* Maximize tensile materials. Disproportionate use of compression elements puts greater demands on energy (and eventually metabolism) for their

production, support and movement as the relative distance between interacting components increase.

* Stabilize through triangulation or prestress. Prestress and triangulation provide more efficient ways to stabilize discrete networks. Triangulation

results in stiff structures whereas prestress provides both flexibility and strength.

* Use structural hierarchies. Structural efficiency is maximized and evolution accelerated through the use of hierarchical networks, which are

themselves discrete structures on a smaller scale.

* Develop self-renewing functional webs through emergence of autocatalytic sets. Once molecules with catalytic functions appear, self-reinforcing

webs of chemical and structural interactions will spontaneously come into existence and expand at the expense of other non-interactive components.

* Enhance functional efficiency through solid-state biochemistry. Most of the chemical and enzymatic functions carried out by living systems

proceed on insoluble scaffolds using solid-phase catalysis. This increases the efficiency of chemical reactions, stabilizes functional networks, and

allows entire metabolic systems to self-assemble with others to create hierarchical structures with enhanced functionality.

Problems and paradigms

1162 BioEssays 22.12

剩余10页未读，继续阅读

weixin_38518376

粉丝: 5
资源: 909

细胞生命起源：基于机械设计与分子化石的理论探讨

细胞生命的起源

python lifegame

apple-mobile-web-app-status-bar-style

Microdosimetry of BNCT

pusch power control

NLOS channel model

Annotation of spatially resolved single-cell data with STELLAR

wsn RF energy harvesting

最新资源